ASTM A312 TP316L TP304L Stainless Steel Seamless Pipe For Oil And Gas

ASTM A312 TP316L TP304L Stainless Steel Seamless Pipe For Oil and Gas

Standard specifications include seamless, longitudinally welded and cold welded austenitic stainless steel pipe for high temperature and general corrosive service. This standard is divided into several grades, each steel grade should determine the required chemical composition C, Mn, P, S, Si, Cr and Cr, Ni, Mo, etc. Process according to desired heat treatment temperature and cooling/testing requirements. It also needs to meet the specified tensile strength and yield strength.

Chemical Composition for TP304 and TP316

A: New designation established in accordance with Practice E527 and SAE J1086

Mechanical Properties

A312 Pipe Manufacturing Types

ASTM A312 pipe covers following manufacturing types (Including hot finished or cold finished):

a. Seamless Pipe (SMLS): It covers stainless steel seamless pipe that manufactured in any process that can not be involved in the welding process.
b. Welded Pipe (WLD): It covers welded pipe that manufactured by an automatic welding process that does not add filler metal during welding.
c. 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.
d. 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.

ASTM A312 pipe shall be free from oxide scale and contaminated iron filings. If the steel pipe is brightly annealed, and pickling, blasting or surface finishing may not be mandatory. The purchaser can request that the finished pipe shall do passivating treatment.

Heat Treatment Methods

ASTM A312 stainless steel pipes shall be furnished in heat treatment condition comply to table 2 of ASTM A312. In case of seamless types, immediately following hot forming while the temperature of the pipes is not less than the minimum solution treatment temperature specified in this table, pipes shall be individually quenched in water or rapidly cooled by other means (direct quenched).

B: Minimum, unless otherwise stated
C: Quenched in water or rapidly cooled by other means, at a rate sufficient to prevent reprecipitation of carbides, as demonstrable by the capability of pipes. heat treated by either separate solution annealing or by direct quenching, of passing Practices A262, Practice E. The manufacturer is not required to run the test unless it is specified on the purchase order (see Supplementary Requirement S7). Note that Practices A262 requires the test to be performed on sensitized specimens in the low-carbon and stabilized types and on specimens representative of the as-shipped condition for other types. In the case of low-carbon types containing 3% or more molybdenum, the applicability of the sensitizing treatment prior to testing shall be a matter for negotiation between the seller and the purchaser.

Mechanical Test

Mechanical test including heat treated condition, Transverse or Longitudinal Tension Test or Flatten Test.

Transverse or Longitudinal Tension Test

For lots of not more than 100 pipes, one specimen shall be taken for tensile testing. For lots of more than 100 pipes, two specimens shall be taken from two pipes for tensile testing.

Flatten Test

For material heat treated in batch furnace, (by quenching after hot forming or in a batch-type furnace equipped with recording pyrometers and automatically controlled within a 30℃ or less range) 5% of steel pipe should be taken from each heat treated lot for flattening test.
For material heat treated in the continuous furnace, sufficient number of pipe to constitute 5% of the lot, but in any case not less than 2 lengths for flattering test.