One More Step Become Mechanical Engineer

I really feel so glad that I'm already first Interview in Jakarta with Tsukisima Kikai PT, and this week I will proceed my second interview in Pontianak and I hope I can pass this interview too, insya Allah. By the way Piping and Fabrication would like to say thank you to Mr. Sugeng Riyadi because he already give me a chance and opportunity to get this job and don't worry I will keep the promise.

And to the visitor of this blog, Piping and Fabrication will continue posting, of course I will post about my job which is Mechanical and Piping, and I will also attached more pictures, because I need that too as my documentation. Don't worry there will be more and more information that I will gave to all of you.

Once again, thanks to all of you who already supporting me.

My Last Duty on Water Treatment Project Line 5

This is probably the last job for me on Water Treatment Project Line 5, because my contract will end this month, and maybe I will find something new or new job. I don't know, maybe to another region or another province, but that's doesn't matter at all.

Piping and Fabrication will always on and ON, because I really like to share all the knowledge that I have to everyone, and that's why I will always love to blogging on Piping and Fabrication and my other blog.

To everyone who already supporting me, especially my team and all my friend, it's nice to work with you and forgive everything I've done if there is something wrong with that and I will miss you friends.

Flange End Connection

Today, Piping and Fabrication will talk about Flange-End Connection and I hope this topics will helpful for anyone who looking for knowledge about Piping System.

Flange Types

 The flange-end connection defines the way in which it is attached to the pipe. The following are commonly available standard flange end types:

Weld-Neck (WN) Flange. Weld-neck flanges are distinguished from other types by their long, tapered hub and gentle transition to the region where the WN flange is butt-welded to the pipe. The long, tapered hub provides an important reinforcement of the flange, increasing its strength and resistance to dishing. WN flanges are typically used on arduous duties involving high pressures or hazardous fluids.

The butt-weld may be examined by radiography or ultrasonic inspection. Usually, the butt-welds are subject to visual, surface, or volumetric examinations, or a combination thereof, depending on the requirements of the code of construction for piping or a component. There is, therefore, a high degree of reliability in the integrity of the weld. A butt-weld also has good fatigue performance, and its presence does not induce high local stresses in the pipework.

Socket-Weld (SW) Flange. Socket-weld flanges are often used on hazardous duties involving high pressure but are limited to a nominal pipe size NPS 2 (DN 50) and smaller. The pipe is fillet-welded to the hub of the SW flange. Radiography is not practical on the fillet weld; therefore correct fitting and welding is crucial. The fillet weld may be inspected by surface examination, magnetic particle (MP), or liquid penetrant (PT) examination methods.

Slip-on Flanges. Slip-on flanges are preferred to weld-neck flanges by many users because of their initial low cost and ease of installation. Their calculated strength under internal pressure is about two-thirds of that of weld-neck flanges. They are typically used on low-pressure, low-hazard services such as fire water, cooling water, and other services. The pipe is ‘‘double-welded’’ to both the hub and the bore of the flange, but, again, radiography is not practical. MP, PT, or visual examination is used to check the integrity of the weld. When specified, the slip-on flanges are used on pipe sizes greater than NPS 2½  (DN 65).

Composite Lap-Joint Flange. This type of flanged joint is typically found on high alloy pipe work. It is composed of a hub, or ‘‘stub end,’’ welded to the pipe and a backing flange, or lapped flange, which is used to bolt the joint together. An alloy hub with a galvanized steel backing flange is cheaper than a complete alloy flange. The flange has a raised face, and sealing is achieved with a flat ring gasket.

Swivel-Ring Flange. As with the composite lap-joint flange, a hub will be buttwelded to the pipe. A swivel ring sits over the hub and allows the joint to be bolted together. Swivel-ring flanges are normally found on sub–sea services where the swivel ring facilitates flange alignment. The flange is then sealed using a ring-type joint (RTJ) metal gasket.

Blind Flange. Blind flanges are used to blank off the ends of piping, valves, and pressure vessel openings. From the standpoint of internal pressure and bolt loading, blind flanges, particularly in the larger sizes, are the most highly stressed of all the standard flanges. However, since the maximum stresses in a blind flange are bending stresses at the center, they can be safely permitted to be stressed more than other
types of flanges.

Waiting for Raw Water (Actiflo) Pic. 1 Re-Start Again

It's been too long for Piping and Fabrication to wait Raw Water Line drawing 1 to continue again, there is still much work to do on Raw Water Line, including huge pipe size which is DN800 or 32 inch that we have to fabricate and erection.

Below here is an isometric drawing for Raw Water Line and almost 70% from that line is not finish yet, and we hope we can have enough man power to finish those line.

Isometric for Raw Water Line drawing No. 1

Can we finish those line in time? we hope we can do it, it's up to many circumstances, technical or non technical situation.

This is Piping & Fabrication write for you all just for information and share. Thanks for visiting!

THE PROCESS OF JOINT INTEGRITY

THE PROCESS OF JOINT INTEGRITY
This is what we want to see and this is also what Piping and Fabrication mean to keep ON AIR until now, to provide us with valuable information like this, enjoy it.

To assist in managing a process, ask yourself the following questions: why, what, who, and how? Why do we need a Flange Joint Integrity program? This was addressed in the previous section, ‘‘Cost of a Leak.’’ The stakes are enormous. A Flange Joint Integrity program will help improve plant safety and reliability while reducing its environmental impact. What do we need to control? The operating environment, the components, and assembly all need to be controlled. Who do we need to control? The designers, field operatives, and supervisors. How do we control? Train personnel to required competency. Design components using latest engineering standards. Develop best practices for assembly and maintenance. Implement a quality assurance program that provides traceability and ensures compliance to specifications. There are over 120 variables that affect flange joint integrity. These can be controlled through the following categories:
● Environment (internal and external)
● Components
● Assembly

The internal environment outlines the design and operating conditions of temperature, pressure, and fluid. With the external environment, consideration is given to location of the flange, whether it is operating in air or sub-sea, and externally applied piping loads. An understanding of the environment is crucial to the design and selection of the appropriate components with the correct assembly methods. The components include the most appropriately designed and selected flange, gasket, and bolting, commensurate with the risk dictated by the environment. Assembly includes checking the condition of the components and proceeding according to established procedures. Proper assembly requires that
● Flange faces meet the standards
● Gasket-seating stress is achieved
● Bolts, nuts, and gaskets are free of defects
● Appropriate lubrication is used

Execution requires trained, competent people using the correct tools and following procedures.

Thanks for Visiting Piping and Fabrication and see you always.

Fabrication Practices which is Cutting and Bevelling

Fabrication Practices

Now Piping and Fabrication will start again to write about all what we need in Piping System, and now we entering with Fabrication Practices which is Cutting and Beveling. 

The methods of cutting plate or pipe to length can be classed as mechanical or thermal. Mechanical methods involve the use of saws, abrasive discs, lathes, and pipecutting machines or tools. Thermal methods are oxyfuel gas cutting or electric arc cutting. Oxyfuel gas cutting is a process wherein severing of the metal is effected by the chemical reaction of the base metal with oxygen at an elevated temperature. In the cutting torch, a fuel such as acetylene, propane, or natural gas is used to preheat the base metal to cutting temperature. A high-velocity stream of oxygen is then directed at the heated area resulting in an exothermic reaction and severing of the material. Oxyfuel gas cutting is widely used for cutting carbon steels and low alloys. It does, however, lose its effectiveness with increasing alloy content. For higher alloy materials, some form of arc cutting is required. Plasma arc cutting is the process most frequently employed. It involves an extremely high temperature (30,000 to 50,000°K), a constricted arc, and a high-velocity gas. The torch generates an arc which is forced to pass through a small-diameter orifice and concentrate its energy on a small area to melt the metal. At the same time a gas such as argon, hydrogen, or a nitrogen-hydrogen mixture is also introduced at the orifice where it expands and is accelerated through the orifice. The melted metal is removed by the jetlike action of the gas stream.

Because oxyfuel gas and arc cutting involve the application of heat, preheating may be advisable in some cases. Weld end bevels can also be prepared by the mechanical or thermal methods just described. Both mechanical and thermal methods are used to apply the V bevel, which is used in the vast majority of piping applications. For compound and U bevels or those which may involve a counterboring requirement, horizontal boring mills are most appropriate. Various factors to be considered in selecting a weld end bevel are discussed in the section, ‘‘Welding Joint Design.’’

Finished Hydro Test for Sand Filter or Multigrade Line

Finally we can completed the Sand Filter Line with finished Hydro Test 10.7 Bar. Piping and Fabrication just want to inform all of you that Sand Filter Line is Done, just few more Joint to the Suction Pump and we plan that will finish fabrication and install in this week.

 10.7 Bar Pressure on Hydro Test Display on Pressure Gauge at 14.45 WIB

Pressure still remain 10.7 Bar on the one hour Holding Time

And now we can focus to the Additional Work for WTP Project such as Fill Softener Tank with Resin, Modification Frontal Piping on Softener Tank, etc.

We never boring to Thanks to the teams and anyone who get involves in this WTP Project. Congratulations Teams, We still have Raw Water Drawing 1 waiting to get our touch. 

Evaluation for Water Treatment Project

In the end of Water Treatment Project for all the lines such as Filter Water, Soft Water, Raw Water, Sand Filter, Dynasand and etc, including all the Equipment or Tank, Multigrade Tank, Softener Tank and Demin Water Tank, there is so many thing we can learn from that project.

It's really hard to control people or can we call Man Power, because we have a big hope to them, when we hire them, they will do as professional worker, but the fact is we have to make them work, teach them how to work, and told them how to work and that's really such a big problem for me and my team. But, we have to take that responsibility, because we can't hire another worker, they all the same, mostly they can't work especially helper.

Luckily that we had very competent and good leader, so they can arrange all that worker, even we know that's really hard but we have to use them. Not mention the users want to do this, want to do that, like they never know the problem on the field, everything can goes wrong if we push them too much.

Piping and Fabrication only hope everyone will understand that we already work as maximum as we can, as hard as we can and we can do nothing more than it, this is the best what we can do for now. We hope, we really hope.

Thanks for everyone who supporting us to finish this WTP Project, especially my teams, once again thank you very much.

Soft Water Line is Done

Same like Filter Water, Raw Water and Dynasand, Soft Water is Done and we already finish Hydro Test for Soft Water too. Piping and Fabrication will inform this to all of you just to inform to anyone who involve with this process.

But, still there is still plenty of work that we must done in short of time, next is Sand Filter and Softener Tank. Under my supervise and Mr. Fandi, we will try to finish Softener Tank this week, because next week all line has to running to supply water for Fiber Plant Line 5.

Once again, thank you to everyone who involve with this project and of course my team, congratulation Teams! I don't know how to thanks to all of you, because I've seen myself that Soft Water Line drawing is really different with actual site condition, there is too many modification we have to do, such as cut and re-weld, different size, different elevation, etc.

Filter Water Line is Completed with Successful Hydrotest

I know it's been a little bit late when I inform this, because probably it's almost few weeks ago that Filter Water Line is completed. We are glad that we can finish the Filter Water on time, of course with much help from my teams and the others. Without them, we are nothing. Filter Water Line completed with Hydro Test process with almost 11 Bar Pressure and we found no leakage.

Here it is the pictures of Hydro Test, we start from 16.45 to fill the water in, and at 17.50 the pressure start stabilize and we start holding time about 1 hour and finish about 19.00 WIB. This is Piping and Fabrication Reporting.

Pressure at 11 Bar for Filter Water Hydro Test

Starting Holding Time at 17.50

Filter Water is Completed

Once more we are thanks to someone always helping us which is Mr. Pandi, because he always lead us and warn us if there is some problem with our job, and of course to my teams, Congratulations Teams!

Replace DN1400 Outlet Dynasand with The New One

May be this DN1400 Outlet Dynasand it's too old, too many corrosive and need to be replace with the new one, and on the Water Treatment Plant (WTP) Project, Replacing DN1400 Outlet Dynasand is one of the line that we have to finished as soon as possible.

Piping and Fabrication has few pictures when we replacing the Old DN1400 Outled Dynasand with the new one, smaller but more effective. And also thank you to everyone who involves with this job and once again thank you very much.

DN1400 Outled Dynasand (previous)

Erection DN800 Pipe Outled Dynasand (Processing)

DN800 to DN600 Outlet Dynasand (New One)

I hope all the line can finish on time without any major problem. Thanks for visiting and good luck!

All The Line on WTP Project has to Finish on 15 October 2012

Bad News for our team, WTP Team, we have to finish all the Line, including sand filter and soft water line at October, 15, 2012, and that's really make me and my teams have to think and work faster. Piping and Fabrication try to find the solution for this situation, and we really hope that we can finish this project on time.

Not mention I have another instruction that the Raw Water Line need to revision again, because we have to follow the process department with they new ultrasonic flow meter. And also they want to finish the revision only on three days and I just can hope there will be no Re Hydro Test for that line.

Completed Line Raw Water Drawing 1 & 2

Finally we completed Raw Water Line for Drawing 1 & 2 (Inlet Actiflo), and we also already completed Radiography, Flushing and Hydro Test for the line. Me and My Team finished this Raw Water or Actiflo Line in time, even we know there is still a few problem during that process but, finally we made it. Thank you to anyone who get involve with this job and this is few pictures and photos when Piping and Fabrication doing Flushing and Hydro Test.

 Flushing Process

 Flushing Process

 Hydro Test at 10.7 Bar Pressure

And the good news is, there is no leakage found during that process and Congratulation Teams!

How Can I Finish This WTP Project?

That's the question that I want to ask to my Boss, because I can't get enough tools, enough man power and enough times to finish this WTP Project on times. Not mention all the tank and equipment that we have to setting up in the same times. That's why me and Piping & Fabrication will talk to the boss and make decision to add more tools, man power (quality man power) and also all the facility I need.

I think that's the only way to get this project finish on time or the company will loose much money and times if the project delay or can't finish in time.

ERECTION MULTIGRADE (SAND FILTER) TANK

Finally Multigrade Tank arrived in the SPV Plant and me and my team can start erection the tank. Because if this multigrade tank not finish erection yet, the others job will be delay by it. And Piping and Fabrication show the pictures of the process of Multigrade Tank when it erection, put the tank on the base.

Piping Erection for Filter Water Line

Continuing again with WTP Project, and now at Demin Plant, we doing Piping Erection for Filter Water Line. It’s really hard place to do the piping erection, because we do this erection inside Demin Plant building and we only have small space and we can’t make any mistake. Because if something goes wrong, the existing pipe and tank will crush by that pipe.

 Manually Piping Erection at Demin Plant

With a very little space between the wall and existing pipe and tank, 

we have to do piping erection manually

So we really have to extra carefully in this process, and Piping and Fabrication believe that our man can do this one, because they have experience for this kind of situation. 

The planning is, after we complete all this Filter Water Line, and all the support and civil work is complete also, we will make this team to do the erection in the same location with another line, which is Soft Water Line, but we still waiting for that time, and I hope that will happen soon.

Water Treatment Project Still on The Way

After almost a few months Piping & Fabrication not posting, because of the Water Treatment Project (WTP) is still on the progress, so I can't do much on the office, cause I have to supervise and control the project and make sure that project is running well.

After almost more than a month, our WTP project is already reach 46% from total 12000 inch dia, and it still doesn't make me happy because we don't have enough worker to do that project (less workers). But, on the other side Piping and Fabrication feel so happy that we can prove to everyone, even we only have no more than 20 persons, but we still can reach more than 45% until now.

So much people doesn't believe that me and my team can do the WTP project in time, but we already prove it to anyone that we can do it and silent them with that progress.

and for everyone, Minal Aidin Wal Faidzin (Mohon Maaf Lahir dan Bathin). Thank you very much.

Catch the Progress on the Pipe Rack Line 5 Progress

It's been almost a month since Water Treatment Plant Project Line 5 is start, and it's really takes a lot of times and energy for me. While the other project which is Pipe Rack Line 5 is almost reach the Dead Lines and that means all the water lines has to hand over to the users in July, 25, 2012, and that's mean we only have few weeks to finish all the water lines in the pipe rack line 5.

Piping and Fabrication now will talk about what is the problems on this pipe rack line 5 project, and how can we solve all the problems? After we had a meeting with all the leaders, including staff from the center office, we decide that all the critical lines must be start with special teams and all the requirements for them we have to provide everything what they wants, including consumables, equipment and even transportation to mobilize the material to the site.

So, I have to send two welders on WTP Project to Pipe Rack, because they are also need more welders to complete the task "On Times". Even now I have to think harder, how do I have to catch the progress with less welders? I hope there is another solutions for me and my teams, also for Pipe Rack teams.

ERECTION PIPE AT WATER TREATMENT PLANT

This is really exhaust day to all of us at site project, including myself. with Piping and Fabrication, I will share the experience when me and my team has to finish Shutdown with only four hours limitation, because the machine will running again. 

With all the preparation that we already prepare about few days ago, everything almost run according to the schedule, except in few line that I have to cut and re-weld pipe line DN300 because it's not has good gap to weld. And when we have to finish all the line with 4 hours left, so we do anything necessary to finish the job so the plant can running again.

I know this experience with Erection Pipe at Water Treatment Plant during Shutdown will never forget, because we have small bonus from the users and that's make me and my team work as harder we can do. and here it is few pictures when we do the erection pipe DN300 and install valve at Water Treatment Plant.

Erection Pipe

Cut and Re-Weld Pipe

The Pipe has been joined

That's all what Piping and Fabrication can told about Erection Pipe at Water Treatment Plant during 4 Hours Shutdown.

Urgently Job for Hot Tapping at WTP Project

I know this is too hard for me to do it myself, not even if I have to do with my teams but if there is no equipment and mobilization for our teams, it's impossible to finish this WTP Project on time. Not mention for Hot Tapping Job, it's really urgent, because we can't stop the machine or request for shut down, that's will stop all the production process.

And with all the Piping and Fabrication job about 12 thousand Inch Dia, I think I have think another strategy for this WTP Project. Including all the report and material issue that has been delayed for few days. But, I believe this will get better soon, same as like Pipe Rack Project. I hope.

TUBING

Like Piping and Fabrication said in the last post, that will provide another useful post and now we entering chapter of Tubing.

Copper, aluminum, steel, and stainless-steel tubing are frequently used in hydraulic, pneumatic, and sampling systems. Installation is most often concerned with protection of such materials from damage, since they are often associated with control systems. The manner of protection is left to the designer’s judgment. Lighter wall tubing is often bent using small compression-type benders. Tubing is joined to itself and to pipe-size fitting and components with a variety of proprietary tubing fittings.. Some heavier-wall stainless-steel tubing is welded using specially designed socket welding fittings, GTAW welding with filler metal added is used for such applications. Pipe Supports This section offers some thoughts on the installation of piping supports. The design, manufacture, and influence of supports on the system flexibility.

As pointed out earlier, economics and efficiency dictate that it is preferable to install the permanent supports for a system as the first step, thus minimizing the need for temporary supports. In so doing considerable judgment should be exercised, since there can be minor variations between the as-designed and as-installed line location. Resilient and constant-effort support should be locked with stops to preclude change in supporting effort as the line is being installed. Only after the line has been completely welded, tested, and insulated should the stops be removed. Once removed, the resilient and constant-effort supports should be carefully adjusted to their ‘‘cold’’ positions. This may take several iterations, since adjustment of any one will change the loading on the adjacent ones. Systems with multiple constant-effort supports can be especially troublesome. Since the support design is most often based on theoretical values of weight of the pipe, insulation, and the fluid, there will be some difference between the actual and calculated supporting effort. Where rigid supports are involved, this variation will be taken up automatically. Where a system is designed with multiple resilient or constant-effort supports, every effort should be made to incorporate one or more rigid supports in the design to absorb the variation between actual and theoretical loads. Otherwise it may be necessary, with the approval of the designer, to modify the spring load-carrying settings. As the line goes to operating temperature, it should be carefully observed to assure that there are no unforeseen interferences with its required expansion, particularly at nearby structures, floor sleeves, or adjacent lines or by restrained branch connections. Some modification may be required to assure free expansion of the line. All resilient supports and constant-effort supports should be checked during initial start-up to assure that they are functioning properly, and after the line has been at operating temperature for several hours, they should be checked to verify that they are in the required ‘‘hot’’ operating condition. It may be necessary to readjust some units to match the calculated ‘‘hot’’ loading. These settings should be checked on a regular basis for the first few weeks of service, particularly in systems operating in the creep range, since the temperature will begin to relieve locked-in construction stresses, and the line may choose a different, more relaxed location. Readjustments may be required. If after some time in service, the resilient and constant-effort supports still require significant adjustment (i.e., the system cannot be balanced), a complete review of the flexibility analysis, expansion calculations, weight calculations, hanger, design, and installation procedures should be made to determine the cause. Resilient and constant-effort support units which are not functioning in the spring range (i.e., they have become ‘‘solid’’ or ‘‘loose’’) may impose undesirably high stresses in the line if they are not corrected, which can lead to premature failure or significantly reduced system life.

Leak Testing

At one time, complex shapes were pressure-tested to determine their suitability for the service intended. This involved stressing the component to a point above service stresses, but below bursting stress, and was referred to as a pressure test. Currently most codes require some type of test to determine leak tightness rather than service suitability. The most common method of leak testing for piping systems is the hydrostatic test. Usually this involves water at ambient temperature as the test medium. B31.1 requires that the system be pressurized to 1.5 times the design pressure, ASME III, to 1.25 times the design pressure, and B31.3 requires a test pressure of 1.5 times the design pressure adjusted by the ratio of the allowable stress at test temperature divided by the allowable stress at operating temperature. In each case, however, the test pressure of unisolated equipment or some function of the yield stress of the line material may be a limiting factor. See the applicable code for particulars.

The line must be held at test pressure for at least 10 min, but may be reduced as permitted in the applicable code until the examination for leakage is complete. Depending on the specific situation, alternative test fluids may be employed. As an example, in a liquid sodium system, where water could be very hazardous, or in cases where the possibility of freezing exists, a hydrocarbon or other fluid might be used.

In instances where water or other liquids are unacceptable, or where supports may not be adequate to carry the added weight of water, pneumatic tests may be performed. Pneumatic tests are potentially more dangerous than hydrostatic tests, and extreme care should be exercised. B31.1 and ASME III require the pneumatic test be performed at not less than 1.2 times the design pressure, while B31.3 limits the test to 1.1 times design. In each case, the limits regarding equipment and yield strength previously cited for hydrostatic tests also apply. Prior to the test a detailed review of the section of the line to be tested should

be made with the following in mind:

1. Temporary supports for those sections where the permanent supports were not designed to take the additional weight of the test fluid.

2. Isolation or restraints on expansion joints.

3. Isolation of equipment or valves which may be overstressed at test pressure.

4. Location of test pump and the need for additional test gauges if there is a significant head variation due to elevation differential.

5. Location of vents and drains.

6. Location of a relief valve to preclude excessive overpressure due to possible thermal expansion of the test fluid.

7. Consideration of the probable ambient test temperature relative to the expected brittle fracture toughness of the system materials. Heating the water may be a solution.

8. Alternative test fluid.

9. Accessibility to the weld joints for inspection. Some codes require that the weld joints be left exposed until after the test.

10. Assurance that no part of the system will exceed 90 percent of its yield strength.

It is advisable to prepare a written procedure outlining the scope and boundaries of each test to assure that it is performed in a safe manner. The codes vary a bit on the required test pressures, time at test pressure, pressure during inspection for leakage, and whether alternative tests may be performed. It is advisable to look at each one specifically. 

That's all for now about TUBING and thanks for visiting Piping & Fabrication.

WASTE WATER TREATMENT PROJECT (WWTP)

Starting new Project, which is Waste Water Treatment Plant Project (WWTP), meanwhile Pipe Rack Line 5 project is not finish yet, and that's a big challenge for me as a Coordinator for the project. On WWTP Project also has Piping and Fabrication, Equipment such as Clarifier, Tank, etc, and tomorrow the schedule of meeting for this WWTP Project. When I have to prepare all the requirements for that project, me and my teams start to estimate the Inch Dia for the PIPING jobs and all of that Piping ID is about 12000 InchDia.

Also with the Equipment jobs, it's about 50 Tons, and the schedule of WWTP Project about 3 months, and we still waiting when we have to start this project until the result of tomorrow meeting with the users.

We also have to prepare all the tools such as Grinding Machine, Gas Cutting, Welding Machine, etc. If the stock is available for the project, we just have to start that project without have to think about the tools, or we don't have or less of any tools.

The drawing is also already hand over to us and we hope we ready for this WWTP Project. I think is enough for now, and I hope in the next post I can provide more useful post to all of us, not only tell about the project I've been working on. Thanks for visiting and if there is any question, you can post on comment box.

RENEWAL ISO CERTIFICATE

Yesterday my company on Site Project has an audit for Renewal ISO Certificate for ISO 9001 : 2008, and me is one of the employee who involve directly with that audit. and with our work which is Piping and Fabrication, there is so many thing that we have to check and audit. Start from Safety, JRA, PPE, Documentation, Process and Computerize.

I have to admitted there is few minor in our Site Project and that's make me has to move fast to correct all that minor. with all the jobs that we have to finish by the end of June, so we have to move very fast. I have to increase more man power to catch all the progress that has been left behind about 10%.

I hope with those action we can get the new project which is WWTP Project, inside of that project is all about PIPING and we think we already learn from this Pipe Rack Project, what is the important thing we can do first before start the project.

So, I hope we can get better and better, because our ISO now already Renew and that mean something. Thanks!

How to Make a Ducting Elbow

Sometimes I don't understand why they can't calculate how to make a ducting elbow, and this is really happen in our workshop. And for this one I think this is one of the basic knowledge that every Fitter has to know. And because of that, now Piping and Fabrication will post about How to Make Ducting Elbow and how to calculate it (shown in the picture below).

To find out the Radius of a Long Radius Elbow, this is how to do it. Radius = 1 1/2 x Nominal Size, and that's really simple when we want to learn. And from that calculation we know what is the requirements for the materials, and how many plate we will use to make a ducting elbow.

I think may be this post will enough to them know how to make a Ducting Elbow, and hope they will learn much about Piping.

Sand Blast and Painting

For almost few weeks, Piping and Fabrication can't post this blog, because there is too many problems that I have to solve for Pipe Rack Line 5 Project, and one of them is Sandblast and Painting. We already told to our Sub contractor that all the Steam Line Pipe has to paint with Heat Resistance Paint, including all the support such as shoe and etc. But, when we inspect to the field, they don't do paint as we told. They do the painting without Heat Resistance Paint and that's make our progress delay, because they have to do reworks.

Not mention all the weather problem such as rain, because we can not avoid it, when the rain falls, almost every activity on the Pipe Rack is stop to avoid accident. Now our progress is almost 15% left behind and that's make me have to think, how do I have to cover all those 15%?

This is Piping and Fabrication, I hope this project will finish soon and all the problems will disappear. Thanks for visiting and if you have a suggestion, please comment!

Piping on Pipe Rack

It's been almost the end of April, but our progress on the Pipe Rack Line 5 at South Pacific Viscose still far far away from the target. The target should be 60% in the end of this month, but we only reach 48.98% for over all job on the Pipe Rack. I know there is so many problem on the field when we doing Piping and Fabrication for this job. For example, there is too many Pipe Rack doesn't suit to with the drawing, or too small support, so it's not possible if we put 24" Inch Pipe on that Pipe Rack and also the other problem such as unfinished pipe rack and support. Because all the Pipe Rack and support is doing by Civil.

We can't joint straight because the limitation of pipe rack

We who doing the Piping Job, it's really face the hard situation here, because only one week left but we have to chase 10% delay from the target. We hope everything will be fine as our planning. By the way, today Piping and Fabrication only post about this, because this is very important to me to catch everything on time.

Thanks for visiting and Good Luck.

Cutting, Bending, Welding, Heat Treatment, and Examination

Cutting, Bending, Welding, Heat Treatment, and Examination

Cutting, bending, and welding operations in the field parallel those used in the shop. See the section ‘‘Fabrication’’ in this Piping and Fabrication blog in the older post. and also Mechanical and oxyfuel gas cutting are most commonly used in the field. Plasma cutting may occasionally be used in Piping. 

Bending, if used at all, is limited to small-diameter piping using relatively simple bending equipment at ambient temperatures. Occasionally in order to correct for misalignment, larger-diameter ferritic piping is bent at temperatures below the lower critical. Please note that this procedure is limited to ferritic materials. Any application of heat to austenitic materials will result in sensitization and loss of corrosion properties. See the section ‘‘Bending.’’ For smaller pipe sizes, torches may be used to supply heat, but for larger, heavier-wall materials and where better temperature control is warranted, heat may be applied by induction or resistance heating units in the same manner as local stress relieving. See the section ‘‘Local Heat Treatment.’’ The heating units are applied to the section of the pipe to be bent. The section of the line upstream of the area to be bent should be anchored to preclude translation or rotation of the installed portion of the line. The anchor should preferably be not more than one or two pipe diameters from the area to be heated. Once the bend area has attained the required temperature, a bending force can be applied on the downstream leg of the pipe until the required bend arc has been obtained. Since most ferritic materials still have reasonably high

yield strengths even at lower critical temperatures, care should be exercised. Large bending forces may damage the building structure or crack the line being bent.

Apply a reasonable force for the conditions and allow the imposed stress in the bend arc to be relieved by the heat. Then repeat. Progress in this fashion until the required bend is accomplished. Some small amount of overbending may be required to offset the deflection which will occur in the unheated section of pipe between the heated arc and the pulling device. When the bend is completed and allowed to cool, all restraints may then be removed. Little if any force should be needed to align the downstream joint; otherwise additional bending may be needed to further correct the situation. No further heat treatment of the bend arc is needed since the temperatures applied in this bending method are below the lower critical temperature. Corrections to lines with large section modulus or where the required bend arc is large should preferably be made in a shop since better controls can be exercised.

Field welding is more often than not in a fixed position. Welders should be qualified in the 6G position since this qualifies for all positions. Welding will be done using SMAW,GMAW,FCAW, and GTAW. Somewelding processes can be automated using orbital welding techniques. Such practice can result in fewer repairs, provided the bevels and alignment are within tolerance and the welding parameters are carefully selected.

Field postweld heat treatment also follows the practices outlined in the section ‘‘Heat Treatment’’ for local stress-relieving of ferritic materials. This usually involves induction or resistance heating units with recording devices. For small pipe welds, torch heating using temperature-sensitive crayons to control temperature is sometimes used. Exothermic heating to stress-relieve welds is still used on occasion for outdoor applications where heating rates are not required to be controlled.

Exothermic materials are preformed to pipe contour and sized to reflect the wall thickness and desired stress-relieving temperature. They are placed around the weld and ignited, attaining temperature in 5 or 10 min. The actual maximum temperature attained may vary. NDE in the field will follow the practices outlined in the section ‘‘Verification Activities.’’ Radiography is usually limited to radioactive isotopes, although occasionally X-ray equipment may find a use. Most surface examination is conducted using liquid-penetrant methods, since magnetic particle equipment is not as convenient in the field. Ultrasonics are used for thickness verification and in certain situations as an alternative to radiography of welds when permitted by the governing code.

Mechanical Joints

Threaded joints probably represent the oldest method of joining piping systems. The dimensional standards for taper pipe threads are given in ASME B1.20.1. This document gives all required dimensions including number of threads per inch, pitch diameter, and normal engagement lengths for all pipe diameters. Thread cutting should be regarded as a precise machining operation. For steel pipe the lip angle should be about 25,

but for brass it should be much smaller. Improper lip angle results in rough or torn threads. Since pipe threads are not perfect, joint compounds are used to provide leak tightness. The compounds selected, of course, should be compatible with the fluid carried and should be evaluated for possible detrimental effects on system components. Manufacturers’ recommendations should be followed.

Threading Die

Where the presence of a joint compound is undesirable, dryseal pipe threads in accordance with ASME B1.20.3 may be employed. These are primarily found in hydraulic and pneumatic control lines and instruments. Flanged joints are most often used where disassembly for maintenance is desired. Agreat deal of information regarding the selection of flange types, flange tolerances, facings and gasketing, and bolting is found in B16.5. The limitations regarding castiron-to-steel flanges, as well as gasket and bolting selection, should be carefully observed. The governing code will usually have further requirements. Gasket surfaces should be carefully cleaned and inspected prior to making up the joint. Damaged or pitted surfaces may leak. Appropriate gaskets and bolting must be used. The flange contact surfaces should be aligned perfectly parallel to each other. Attempting to correct any angular deviation perpendicular to the flange faces while making up the joint may result in overstressing a portion of the bolts and subsequent leakage. The proper gasket should be inserted making sure that it is centered properly on the contact surfaces. Bolts should be tightened hand-tight.

Compression sleeve (Dresser) coupling for plainend cast-iron or steel pipe

If necessary for alignment elsewhere, advantage may be taken of the bolt hole tolerances to translate or rotate in the plane of the flanges. In no case should rotation perpendicular to the flange faces be attempted. When the assembly is in its final location, bolts should be made up wrench-tight in a staggered sequence. The bolt loading should exert a compressive force of about twice that generated by the internal pressure to compensate not only for internal pressure but for any bending loads which may be imposed on the flange pair during operation. For a greater guarantee against leakage, torque wrenches may be employed to load each bolt or stud to some predetermined value. Care should be exercised to preclude loading beyond the yield point of the bolting. In other cases, special studs that have had the ends ground to permit micrometer measurement of stud elongation may be used. Flange pairs which are to be insulated should be carefully selected since the effective length of the stud or bolt will expand to a greater degree than the flange thicknesses, and leakage will occur. Thread lubricants should be used, particularly in high-temperature service to permit easier assembly and disassembly for maintenance. There are a great variety of mechanical joints used primarily for buried castiron pipelines carrying water or low-pressure gas. They are primarily of the bell and spigot type with variations involving the use of bolted glands, screw-type glands, and various types of gasketing. The reader is referred to AWWA Standards C 111, C 150, and C 600, and to catalogs for proprietary types. For reinforced concrete pipe,AWWAStandards C 300, C 301,51 and C 302, should be consulted. Compression-sleeve couplings such as the Dresser coupling and the Victualic coupling are widely used for above- and below-ground services, both with cast-iron and steel pipe. Consult the manufacturers’ catalogs for more information. 

INSTALLATION PROCESS ON PIPING AND FABRICATION

INSTALLATION ON PIPING AND FABRICATION

I think everyone who work and involved in the Piping, Maintenance, Fabrication and Mechanical on Piping and Fabrication must know about the whole process from the beginning what the piping system is and here we will talk start from drawing, erection, cold spring, joint alignment and etc.

Drawings

Drawings used for piping system installation may vary greatly. Often orthographic projections of the building showing several systems or single systems, depending on complexity, are used. In many cases single or multiple isometric drawings of a single system are used. These of course are not to scale but are convenient for planning, progress recording, or record keeping when required by quality programs. In all cases where prefabricated subassemblies are being erected, these drawings will have been marked up to show the locations and mark numbers of the individual subassemblies, the location and designations of field welds, and the locations and markings of hangers.

Erection Planning

Planning is vitally important in installing a piping system. Many factors must be considered, among them accessibility to the building location, coordination with other work, availability and accessibility of suitable welding and heat treatment equipment, availability and qualification of welders and welding procedures, rigging, scaffolding, and availability of terminal equipment. Each of the system components should also be carefully checked to assure correctness. Valves and other specialty items in particular should be checked to assure they are marked with flow arrows, that the handwheels or motor operators are properly oriented, and that the material to be welded is compatible with the material of the piping. Special valves for use in carbon steel systems are sometimes furnished as 5 percent chrome material, and thermowells are often not of the same chemical composition as the pipe. This may not be apparent from the drawings Such a preliminary check will indicate the need for alternate welding procedures and preclude problems later.

The location of the work and accessibility to it should be viewed. It may not be possible to install an overly long subassembly after other equipment or building structure is in place. A common practice in the power field is to have large, heavy assemblies often found in the main steam and reheat lines of large central stations erected with the structure. In other cases, a preliminary review may show interferences from an existing structure, cable trays, ducts, or other piping which are not apparent from the drawings. The locations of the terminal points on equipment should be checked to assure that they are correct. The type, size, rating, or weld preparation of the connection should be checked to assure that it will match the piping. Solutions to any problems can be devised with the designer before work starts.

The ideal way to begin erection is to start at some major piece of equipment or at a header with multiple outlets. Install the permanent hangers if possible. If these are to be welded to the structure, some prudence should be exercised, since the final location of the line may warrant some small relocation to assure that the hanger is properly oriented relative to the piping in its final position. Obviously a certain number of temporary supports will be needed. Welding of temporary supports to the building structure or to the piping itself should be avoided or used only with the approval of the responsible engineers. Variable spring and constantsupport type hangers should normally be installed with locking pins in place, assuring that they function as a rigid support during the erection cycle. Where welded attachments to the pipe are involved, it is preferred that they be installed in the shop as part of the subassembly. If possible, the major components of the system should be erected in their approximate final position prior to the start of any welding. This will reveal any unusually large discrepancies which may result from equipment mislocation, fabrication error, or tolerance accumulations. Adjustments or corrections can then be decided upon. Long, multiplane systems can absorb considerable tolerance accumulation without the need to modify any part. Short, rigid systems may not be able to accommodate any tolerance accumulation, and it may be necessary to rework one or more parts.

Cold Spring

Both the B31.1 and B31.3 Codes address cold springing in detail. Cold spring is the intentional stressing and elastic deformation of the piping system during the erection cycle to permit the system to attain more favorable reactions and stresses in the operating condition. The usual procedure is to fabricate the system dimensions short by an amount equal to some percentage of the calculated expansion value in each direction. The system is then erected with a gap at some final closure weld, equal to the ‘‘cut shorts’’ in each direction. Forces and moments are then applied to both ends as necessary to bring the final joint into alignment. Once this is done, it is usually necessary to provide anchors on both sides of the joint to preserve alignment during welding, postweld heat treatment, and final examination. When the weld is completed and the restraining forces are removed, the resulting reactions are absorbed by the terminal points, and the line is in a state of stress. During start-up the line expands as the temperature increases, and the levels of stress and terminal reactions resulting from the initial cold spring will decrease. For the 100 percent cold sprung condition, the reactions and stress will be maximum in the cold condition and theoretically zero in the hot condition. It should be borne in mind that it is very difficult to assure that a perfect cold spring has been attained and for this reason the codes do not permit full credit in the flexibility calculations. Also remember that lines operating in the creep range will ultimately attain the fully relaxed condition. Cold spring merely helps it get there faster. Cold spring was historically applied to high-temperature systems such as main steam and hot reheat lines in central power stations, but this practice is not as prevalent anymore.

For those involved with the repair of lines which have been cold sprung, or which have achieved some degree of creep, caution should be exercised when cutting into such lines since the line will be in a state of stress when cold. The line should be anchored on either side of the proposed cut to prevent a possible accident.

Joint Alignment

In aligning weld joints for field welding it may be necessary to compromise between a perfect weld fit-up and the location of the opposite (downstream) end of the assembly. The weld bevel may not be perfectly square with the longitudinal axis of the assembly. Even a 1/32-in (0.8 mm) deviation across the face of the weld bevel can result in an unacceptable deviation from the required downstream location if the joint is aligned as perfectly as possible. Often such a small gap can be tolerated in the welding. If, in order to maintain the downstream location, the gap at the joint is excessive, the joint should be disassembled, and the land filed or ground as needed to attain the required alignment of the weld joint while still maintaining the required downstream position. Flanged connections should be made up handtight so that advantage can be taken of the bolt-hole clearances to translate or rotate the assembly for better alignment of downstream connections.

Weld shrinkage of field welds may or may not be important in field assembly. In long flexible systems, they may be ignored. For more closely coupled systems, particularly those using GTAW root-pass welding, this factor should be considered. The degree of longitudinal shrinkage across a weld varies with welding process, heat input, thickness, and weld joint detail. See the section ‘‘Layout, Assembly, and Preparation for Welding.’’ In extreme cases closure pieces may be used. Here, the system is completed except for the final piece. A dummy assembly is then fabricated in place and the closure assembly is fabricated to match the dimensions of the dummy assembly with weld shrinkage of the final welds taken into account.

Just to remembering, that what we explain here is according to the ASME Standard.

Cleaning and Packaging

Cleaning and Packaging. Cleaning and Packaging is one of the important aspect that we have to know in Piping and Fabrication, because we need to know what is the best material and way to make good Cleaning and Packaging. Cleanliness of piping subassemblies is a matter of agreement between the fabricator and purchaser. As a minimum the fabricator will clean the inside of the subassembly of loose scale, weld spatter, machining chips, etc., usually with jets of compressed air. For those systems which require a greater degree of cleanliness several options are available. For specific information refer to PFI Standard ES-5 ‘‘Cleaning of Fabricated Pipe.’’39 See also the following specifications published by the Steel Structures Painting Council:

SSPC—SP 2 Hand Tool Cleaning
SSPC—SP 3 Power Tool Cleaning
SSPC—SP 6 Commercial Blast Cleaning
SSPC—SP 8 Pickling
SSPC—SP 10 Near-white Blast Cleaning

For ferritic steels the inside surfaces may be cleaned by turbinizing to remove loosely adhering mill scale and heavy rust. Wire brushing and grinding may also be employed for removal of more tightly adhering scale, rust, etc.; however, the most effective method for removal of tight scale is blasting with sand, shot, or grit.

For guidance on blasting methods and degrees of cleanliness refer to PFI Standard ES-29 ‘‘Abrasive Blast Cleaning of Ferritic Piping Materials.’’ Pickling is an equally effective method of cleaning. It is most often used for cleaning large quantities of straight tubes prior to fabrication or small-size (about NPS 4) subassemblies where blasting is not as effective. Its application is limited by the availability and size of pickling tanks. A hot solution of sulfuric acid (H2SO4) is most commonly used, although cold hydrochloric acid (HCl) is also recommended. See SSPC—SP 8 ‘‘Pickling.’’

For the 9Cr-1Mo-V materials, aluminum-oxide or silicon-carbide grit, sand or vapor blasting is preferred. Steel shot or grit which has been previously used to clean iron-bearing materials should be avoided. Acid pickling should also be avoided since damaging hydrogen embrittlement may occur. Austenitic stainless steels normally do not require cleaning except for a degreasing with solvent-saturated cloths to remove traces of greases or cutting oils. Subassemblies which have been heated for bending or which have been given a carbide solution heat treatment will have a tightly adhering chromic oxide scale. Pickling and passivating in a solution of hydrofluoric and nitric acid will remove the scale and passivate the exposed surface. Here again, the equipment for pickling may limit the size of the subassembly. See ASTM A 380 published by the American Society for Testing Materials.42 Blasting may also be used, but new silica sand or aluminum-oxide grit is required. Sand or grit previously used on ferritic pipe will contaminate the pipe surface with iron particles, and it will subsequently rust. The blasted surface should be treated with a solution of nitric acid to passivate the surface.

For extreme cleanliness, steam degreasing and rinsing with demineralized water may be employed. The external surfaces of pipe may be left as is, painted, or otherwise preserved. See PFI Standard ES-34 ‘‘Painting of Fabricated Piping.’’ Depending on the need for maintaining rust-free interior surfaces, the pipe inside diameter may be coated with different preservatives, or desiccants may be employed during shipping and storage. For shipping, the ends of subassemblies are equipped with some type of end protection to preclude damage to weld end bevels or flange faces during shipment and field handling. See PFI Standard ES-31 ‘‘Standard for Protection of Ends of Fabricated Piping Assemblies.’’

During shop operations, it is common practice to move piping assemblies with overhead or floor cranes, usually with chain or wire rope slings. For austenitic stainless steels and nonferrous materials which could be damaged or contaminated, use of nylon slings is recommended.

Methodology on Piping and Fabrication

Methodology is one of the important thing that we have to know in Piping and Fabrication Systems. There is so many thing and knowledge that we can read here only on Piping & Fabrication.

The ASME Boiler and Pressure Vessel, B31.1 and B31.3, require certain NDEs to be performed in accordance with the methods described in ASME Section V Nondestructive Examination. The pipeline codes, B31.4, B31.8, and B31.11, refer to API-1104 for Radiographic Procedures. In some cases, particularly in visual examination, requirements are given but no specific methodology is stated. In others, alternative parameters or qualification requirements are given. The specific requirements of the individual codes should be consulted.

Qualification Requirements. Qualification of procedures and personnel used in NDEs are required by most codes. When ASME Section V orAPI-1104 are invoked by the referencing code, a written procedure is required and it must be demonstrated to the satisfaction of the AI, ANI, owner, or owner’s agent, whichever is applicable.

Similarly personnel who perform NDEs must be trained, qualified, and certified. The most frequently invoked qualification document is SNT-TC-1A; it is also accepted by B31.1 for qualification of personnel performing visual examinations. Some codes permit alternatives, such as AWS-QC-1

Table A
Acceptance Standards for Visual Examination
The following indications are unacceptable:
1. Crack(s) on external surfaces
2. Undercut on surface greater than 1⁄32 in (1.0 mm) deep
3. Weld reinforcement greater than specified in ASME Table 127.4.2
4. Lack of fusion on surface
5. Incomplete penetration (applies only when inside surface is readily accessible)
6. Any other linear indications greater than 3⁄₁₆ in (5.0 mm) long
7. Surface porosity with rounded indications having dimensions greater than 3⁄16 in (5.0 mm) or 4 or more rounded indications separated by 1⁄16 in (2.0 mm) or less edge to edge in any direction. Rounded indications are indications which are circular or elliptical with their length less than 3 times their width

Source: From ASME B31.1 1995 ed.

Extent of Examination. The applicable code will define the extent of examination required for piping systems under its coverage. The degree of examination and the examination method and alternatives are a function of the degree of hazard which might be expected to occur in the event of failure. Pressure, temperature, toxicity of the fluid, and release of radioactive substances are some of the considerations. Added layers of examinations may be required as the perceived hazard increases.

Accept-Reject Criteria. The applicable code will also define the items to be examined and the accept-reject criteria to be applied. Table A shows the acceptance standards applicable to the visual examination of butt welds under B31.1. Other piping codes have similar but not necessarily identical criteria.

Table B shows acceptance standards for radiographic examination. Indications interpreted as cracks, incomplete penetration, or lack of fusion are not permitted. Porosity and elongated indications are kept within certain limits. The acceptance standards for ultrasonic examination are similar.

Table B
Acceptance Standards for Radiography
Welds that are shown by radiography to have any of the following types of discontinuities are unacceptable:
1. Any type of crack or zone of incomplete fusion or penetration
2. Any other elongated indication with a length greater than
a. 1⁄4 in (6.0 mm) for t up to 3⁄₄ in (19.0 mm)
b. 1⁄3 t for t from 3⁄4 in (6.0 mm) to 21⁄4 in (57.0 mm) inclusive
c. 3⁄4 in (19.0 mm) for t over 21⁄4 in (57.0 mm) where t is the thickness of the thinner portion of the weld
3. Any group of indications in a line that have an aggregate length greater than t in a length of 12 t, except where the distance between successive indications exceeds 6L where L is the longest indication in the group
4. Porosity in excess of that shown as acceptable in Appendix A-250 of Section I of the Boiler and Pressure Vessel Code
5. Root concavity when there is an abrupt change in density indicated on the radiograph

Table C
Acceptance Standards for Magnetic Particle and Liquid Penetrant Examinations
The following relevant indications are unacceptable:
1. Any cracks or linear indications
2. Rounded indications with dimensions greater than 3⁄16 in (5.0 mm)
3. Four or more rounded indications in a line separated by 1⁄16 in (2.0 mm) or less edge
to edge
4. Ten or more rounded indications in any 6 in2 (3870 mm2) of surface with the major dimension of this surface not to exceed 6 in (150 mm) with the area taken in the most unfavorable location relative to the indications being evaluated

Both magnetic particle and liquid penetrant examinations have identical limits. See Table C, Other types of NDEs, such as acoustic emission, bubble testing, and mass spectrometer testing, are not required by the various codes. They can be invoked by contract and the acceptance standards must be a matter of agreement between the contracting parties.

Testing. All of the piping codes outline some type of pressure test to determine leak tightness. Since the completed piping system is usually subjected to some type of test in the field after installation, shop testing of subassemblies is infrequent. In those cases where the assembly cannot be field tested, where welds in the assembly will not be exposed for examination during the field test, and in other special situations, shop testing may be required. Shop testing must meet all of the requirements for field testing. See the section ‘‘Installation’’ for particulars.

Quality Assurance and Quality Control. ASME Section III has very specific requirements for QA programs. ASME Section I has requirements for QC programs. The B31 Piping Codes do not require any formal written program at this time. Refer to these codes for detailed information on this subject.

Examination on Piping and Fabrication

Examination, this chapter like I promise in the last post, Piping and Fabrication will gave to you, I think the description and explanation about The Examination on Piping & Fabrication is detail enough, enjoy your self.
Types of Examinations. When used in the various codes, examination refers to the verification work performed by employees of the fabricator, much of which falls into the category of NDE. NDEs most often referenced by code and applied to the fabrication and installation of piping components and systems are:
•    Visual
•    Radiographic
•    Ultrasonic
•    Liquid penetrant
•    Magnetic particle
Eddy current examination is often used to evaluate the quality of straight lengths of pipe as they are manufactured but is not often used in fabrication activities. Although not referenced by most codes, bubble testing, halogen diode probe testing, or helium pass spectrometer leak testing may be invoked by contract when, in the opinion of the designer, they will contribute to the integrity of the system. While these methods are referred to as leak tests, their methodology is outlined in Article 10 of ASME Section V Nondestructive Examination.

Accept-reject criteria and the extent to which the various NDEs are to be applied are in the applicable code. The following are brief descriptions of NDEs as they apply to piping. For much more detailed information the reader is referred to various publications of the American Society for Nondestructive Testing (ASNT),36 particularly the Nondestructive Testing Handbooks.

1. Visual examination: Visual examination is probably the oldest and most widely used of all examinations. It is used to ascertain alignment of surfaces, dimensions, surface condition, weld profiles, markings, and evidence of leaks, to name a few. In most instances the manner of conducting a visual examination is left to the discretion of the examiner or inspector, but more recently, written procedures
outlining such things as access, lighting, angle of vision, use of direct or remote equipment, and checklists defining the observations required are being used. Visual examination takes place throughout the fabrication cycle along with QA and QC checks. At setup, this would consist of verifying materials, weld procedures, welder qualifications, filler metal, and weld alignment, and on completion of fabrication, such things as terminal dimensions, weld profile, surface condition, and cleanliness.

2. Radiographic examination: When the need for greater integrity in welding must be demonstrated, the most frequently specified examination is radiography. Since the internal condition of the weld can be evaluated, it is referred to as a volumetric examination.

Radiographic sources used for examination of piping are usually X-rays or gamma rays from radioactive isotopes. While X-ray equipment is often used, it has limitations in that it often requires multiple exposures for a single joint, and special equipment, such as linear accelerators, are needed for heavier thicknesses. Although X-ray machines produce films with better clarity, they are not as practical in the field because of space limitations and portability. In the field, radioactive isotopes are used almost exclusively because of their portability and case of access. For wall thicknesses up to about 21⁄₂ in (63.5 mm) of steel, the most commonly used isotope is iridium 192. Beyond this cobalt 60 is used for wall thickness up to about 7 in (179 mm).

Radioactive sources normally used in piping work range in intensity from a few curies up to about 100 curies. Each source decays in intensity in accordance with its particular half-life. As the intensity decays, longer exposure times are required. Iridium 192 has a half-life of 75 days, while cobalt 60 has a 5.3-year half-life. Radioactive sources have finite dimensions and as a result produce a shadow effect on the film. This is referred to as geometric unsharpness, and it is directly proportional to the source size and inversely proportional to the distance between the source and the film. ASME Section V has established limits for geometric unsharpness.

Ideally for pipe, the source is placed inside the pipe and at the center of the weld being examined, with film on the outside surface of the weld, thus permitting one panoramic exposure. Where geometric unsharpness precludes this practice, the source may be placed on the inside on the opposite wall and a portion of the weld is shot. Several exposures will be needed. The source may also be placed outside the pipe and the exposure made through two walls. Again this requires multiple exposures and longer exposure times. A radiograph is considered acceptable if the required essential hole or wire size information on this subject.

3. Ultrasonic examination: Ultrasonic examination is used in piping for the detection of defects in welds and materials as well as for determining material thickness. A short burst of acoustic energy is transmitted into the piece being examined and echoes reflect from the various boundaries. An analysis of the time and amplitude of the echo provides the examination results.

A clock in the equipment acts to initiate and synchronize the other elements. It actuates a pulsar to send a short-duration electrical signal to a transducer, usually at a frequency of 2.5 MHz. The transducer converts the electrical signal to mechanical vibration. The vibration as ultrasound passes through a couplant (such as glycerine) and through the part at a velocity which is a function of the material. As the
sound reflects from various boundaries, it returns to the initiating transducer or sometimes to a second one where it is converted back to an electrical signal which is passed to a receiver amplifier for display on a cathode-ray tube. The horizontal axis of the display relates to time and the vertical axis relates to amplitude. The indication on the extreme left will show the time and amplitude of the signal transmitted from the transducer. Indications to the right will show the time and degree of reflection from various boundaries or internal discontinuities. The ability of an ultrasonic examination to detect discontinuities depends a great deal on the part geometry and defect orientation. If the plane of the defect is normal to the sound beam, it will act as a reflecting surface. If it is parallel to the sound beam, it may not present a reflecting surface and accordingly may not show on the oscilloscope. Therefore, the search technique must be carefully chosen to assure that it will cover all possible defect orientations.

The most serious defect in a pipe butt weld is that which is oriented in the radial direction. The most commonly used technique for detecting such defects is the shear wave search. In this procedure, the transducer is located to one side of the weld at an angle to the pipe surface. The angle is maintained by a lucite block which transmits the sound from the transducer into the pipe. The sound will travel at an angle through the pipe and weld. Being at an angle, it will reflect from the pipe surfaces until it is attenuated. Any surface which is normal to the beam, however, will reflect a portion of the sound back to the transducer and show as an indication on the oscilloscope. If the beam angle and the material thickness are known, the reflecting surface can be located and evaluated.

Prior to and periodically during each search, the equipment is calibrated against artificial defects of known size and orientation in a calibration block. The block must be representative of the material being searched (i.e., an acoustically similar material, with appropriate thickness, outside contour, surface finish, and heattreated condition). A variation of ultrasonic examination can be used to measure material thickness. If the speed of sound within the material is known, the time it takes for the signal to traverse the thickness and return can be converted to a thickness measurement.

4. Liquid penetrant examination: Penetrant-type examinations are suitable for surface examinations only but are very sensitive. They require a fairly smooth surface, since surface irregularities such as grinding mark indications can be confused with defect indications. The surface to be examined is thoroughly cleaned with a solvent and then coated with a penetrating-type fluid. Sufficient time is allowed to permit the fluid to penetrate into surface discontinuities. The excess penetrant is removed by wiping with cloths until all evidence of the penetrant is removed. A developer which acts somewhat like a blotter is then applied to the surface. This an indication. Obviously, the success of the examination depends on the visibility of the indication. To enhance this, the penetrant contains colored dyes which can be seen under normal light, or fluorescent dyes which are viewed under ultraviolet light. The most common case is a red dye penetrant with a white developer.

        FIGURE A6.26 Ultrasonic shear wave search. (a) Search arrangement; (b) oscilloscope

5. Magnetic particle examination: Magnetic particle examination is essentially a surface-type examination, although some imperfections just below the surface are detectable. This type of examination is limited to materials which can be magnetized (paramagnetic materials), since it relies on the lines of force within a magnetic field.

The item to be examined is subjected to a current which will produce magnetic lines of force within the item. The surface is then sprayed with a fine iron powder. The powder will align itself with the lines of force. Any discontinuity normal to the lines of force will produce a leakage field around it and a consequent buildup of powder which will pinpoint the defect. The examination must be repeated at 90° to detect discontinuities which were parallel to the original field. There are a great many variations of magnetic particle examination depending on the manner in which the field is applied and whether the particles are wet or dry and fluorescent or colored.