API 5L Application

The pipe material A 106 Grade B is produced in only seamless type which is preferred in process areas, where API 5L can be produced in seamless, seam welded or spiral which is preferred in cross-country pipelines because of its inexpensive. And all designers don't prefer to use the seam welded nor spiral in process facilities where there is some hazard.

The chemical and mechanical properties of A 106 Grade B is better than when compared with those for API 5L. Also, the characteristics of A 106 Grade B at higher temperatures is better, where we can use A 106 Grade B in boilers, fired heaters, heater treaters, fired tubes, ... etc. where may be there is a chance for direct subject to flame of burners, where you can't use API 5L at these situations.

It has to be borne in mind that there are slightly different requirements. Boiler pipes will need to be good for fairly high temperatures, sometimes with flame impingement. pipelines generally do not have this requirement (although subsea gas pipelines can reach 550 deg C or more when "packed". An important property of pipeline steels is the resistance to crack propogation. For a gas pipeline any crack must not grow faster than the speed of flame propogation of the gas. Many years ago therewas at least one case reported where the pipeline "unzipped" too fast and the flame followed the split for a considerable length. I understand API carried out a great deal of work on the pipeline steel (API 5L) to eliminate this problem. The higher pressures used today (mainly in subsea pipelines) requires careful consideration of pipe damage propogation.

technically very good answer

The metallurgical values (chemistry) in each of these pipes do not vary much at all. The nomenclature (A106, SA106, etc.) is the greatest difference. The API references the pipe as X42, X65, etc. ASME uses SA106, SA53, etc. ASTM uses A106, A53, etc.

The API number basically references the nominal yield strength of the pipe.

The API 1104 code is used for "welding of pipelines and related facilities". Inside the process units, the ASME code is more frequently used due to the fired or unfired pressure vessels contained in the units. Thus the SA or A106 Grade B is the nomenclature for the pipe.