Regarding pipeline construction issues
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Hello, sea friends! We have many types of project pipelines, as well as a wide variety of materials. There are seamless pipes and welded steel pipes; among the carbon steel materials available are 20#, A627, P91, and L22. There are also many types of stainless steel, as well as copper-based stainless steel alloy pipes and oxygen pipes that have been degreased. I know that some pipeline drawings require post-weld heat treatment; however, the list of those specific items that need heat treatment is not yet indicated in the table. Generally, what types of pipes require heat treatment? I know that the SH3501-2013 standard contains two tables regarding pre-welding heating and post-welding heat treatment; please refer to the attached images. For my project, there are DN80 pipes with a thickness of 25 mm; they are made of carbon steel of grade A672 and are seamless pipes that will be assembled and welded on site. Is preheating before welding necessary? How can the quality of oil and grease removal from oxygen pipelines be ensured? On-site management is chaotic; pipes, whether made of carbon steel or stainless steel and regardless of their diameter, are never sealed, nor are their flange surfaces protected. As soon as it rains, the outer surface of the stainless steel pipes is covered in mud and footprints.
After degreasing the oxygen pipelines, it is essential to check whether they meet the required standards. If there are no flanges at either end, the pipes can be wrapped with shielding film and then covered with weatherproof fabric, with an additional layer of wood placed on top for protection. It is recommended to carry out degreasing after the pipes have been installed, unless the pipes are located inside a cold box and need to be cleaned before installation, in order to avoid any residual issues. If you need acid cleaning and passivation for pipeline equipment, or degreasing cleaning for oxygen pipelines, please contact us.
Your DN80 carbon steel of A672 with a thickness of 25 requires heat treatment
Yes, according to the SH3501-2013 standards, heat treatment is required, but the specifications provided in the design do not mention any requirement for heat treatment. I don’t know what to do either? Was it done according to the design or according to the specifications?
Okay. I asked them to follow the standard requirements
Hello, such projects are all contacted by the construction companies themselves; we are not involved in them. Thank you!
Oil and grease removal must be carried out before installing pipes and valves; it should also be done after the pipes have been installed, as part of the system circulation process
Here’s the simplest way to identify them: check the pipe grade table for the pipe number; all pipes marked with R require heat treatment. For example, 2TB12R – those familiar with the SEI project will understand it at a glance. Another thing to check is the first drawing or the instructions, which will provide you with explanations.
The design will certainly include markings for pipelines that require heat treatment. Carefully examine the pipeline design specifications, pipeline grade tables, pipeline lists, or pipeline ISO diagrams