What is the difference between seamless and welded pipe?
Seamless pipe is formed from a solid billet without a weld seam and is preferred for high-pressure, high-temperature and sour service. Welded pipe — ERW, HFW, LSAW or SSAW — is formed from plate or strip and welded, and is more economical in larger diameters and thinner walls. API 5L covers both; ASTM A106 is seamless only. The project piping class states which is acceptable.
What does PSL2 mean on API 5L pipe?
API 5L defines two product specification levels. PSL1 is the standard quality level. PSL2 adds mandatory Charpy impact testing, tighter limits on carbon equivalent and chemistry, mandatory non-destructive examination, and traceability requirements. Transmission pipelines, sour service and offshore work are normally specified PSL2.
When is a weld neck flange used rather than a slip-on?
A weld neck flange has a tapered hub butt-welded to the pipe, giving full-strength joint integrity and good fatigue performance; it is specified for high pressure, high temperature, cyclic and hazardous service. A slip-on flange slides over the pipe and is fillet-welded inside and out; it is cheaper and easier to align but rated lower for fatigue and is generally limited to lower-pressure utility service. Most oil and gas piping classes specify weld neck.
What is a spiral wound gasket and how is it specified?
A spiral wound gasket is made of alternating windings of a metal strip and a soft filler, usually 316 stainless steel with flexible graphite or PTFE, with an outer centring ring and often an inner ring. It is specified by flange size and class to ASME B16.20, winding and filler material, and ring materials. It is the standard gasket for raised-face flanges in oil and gas service.
What should be on the mill test certificate?
The heat number, the material specification and grade, chemical analysis, mechanical test results — tensile, yield, elongation, and Charpy impact where required — hardness where specified, the hydrostatic test and any NDE performed, and dimensional confirmation, all signed by the manufacturer’s inspection department. The certificate should be EN 10204 3.1 as a minimum, and 3.2 where the project requires third-party witness.
Can pipe be supplied dual-certified?
Yes. Seamless carbon steel pipe is commonly manufactured to meet both API 5L grade B and ASTM A106 grade B, and stainless pipe to both A312 and A358 or A778. Dual certification is stated on the mill certificate and allows one stock to serve both piping classes. Specify dual certification on the enquiry where the project piping class permits it.
Where is the material sourced from?
CRS PLUS sources pipe, flanges and fittings from its qualified supplier base of API-licensed and ISO-certified mills and forges in China, India, Europe and the Gulf. Origin and the certifying body are stated on each quotation. CRS PLUS does not name manufacturers on this page and holds no distribution or agency agreement with any of them.