ASTM A312 stainless steel pipe and tube covers following manufacturing types (Including hot finished or cold finished):

1. Seamless Pipe (SMLS): It covers stainless steel seamless pipe or tube in hot rolling or cold drawn.

2. Welded Pipe (WLD): Welded by an automatic welding process that does not add filler metal when welding.

3. Cold Worked Pipe (HCW pipe): The heavy cold-worked pipe that apply cold working of not less than 35% reduction in thickness

of both wall, and welded to the welded pipe prior to final annealing. Do not use fillers during welding.

4. Welded and HCW pipe: Welded pipe and HCW pipe of 14 and smaller than NPS 14 shall have a single longitudinal weld.

After approval by the purchaser, the welded pipe and HCW pipe with an NPS greater than NPS 14 shall have a single longitudinal weld

or shall be manufactured by forming and welding two longitudinal sections of flat stock.

So each welds are to be tested, inspected, inspected or treated.