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.
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.
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