Mikeqc1
Read this the other day and figured it answered your question.
Most rounds are ASTM A53 Grade B pipe or round ASTM A500 HSS that have not been pressure tested. You may receive round ASTM A500 instead of ASTM A53 Grade B for two reasons: ASTM A500 has a greater yield strength than ASTM A53 Grade B, and it is manufactured to the same dimensions as ASTM A53 pipe. It is interesting to note that HSS producers produce pipe-like cross sections in ASTM A500, but due to the overlap in the two standards, such round tubular sections are offered as ASTM A53 Grade B without pressure testing. They are essentially ASTM A500 products that have been downgraded and sold as ASTM A53 Grade B pipe!
http://structuralsteeldetailer.us/materials.htmlMarshall