ASTM A135, identical with ASME SA-135, is the standard specification for electric-resistance-welded steel pipe. It covers two grades of ERW steel pipe in NPS 2 to NPS 30 [DN 50 to DN 750], with nominal (average) wall thickness up to 0.500″ [12.7 mm], and in nominal sizes NPS 3/4 to NPS 5 [DN 20 to DN 125] with nominal (average) wall thickness 0.083″ [2.11 mm] to 0.134″ [3.40 mm], depending on size. Pipe having other dimensions may be furnished provided such pipe complies with all other requirements of this specification.
The ASTM A135 ERW steel pipes are intended for conveying gas, vapor, water or other liquid; only Grade A is adapted for flanging and bending. The selection of this ERW pipe for various applications depends on its dimensions, properties, and conditions of service. The pipe may be furnished either non-expanded or cold expanded at the option of manufacturer. When pipe is cold expanded, the amount of expansion shall not exceed 1.5% of the outside diameter of pipe size.
Mechanical Properties
| ASTM A135 | Grade A | Grade B |
|---|---|---|
| Tensile Strength, min, ksi [MPa] | 48 [330] | 60 [415] |
| Yield Strength, min, ksi [MPa] | 30 [205] | 35 [240] |
| Elongation, min, % | 35 | 30 |
*The yield strength shall be determined by the offset method utilizing 0.2% of the gauge length or by the total extension under load method using 0.5% of the gauge length.
*The yield strength shall be determined by the offset method utilizing 0.2% of the gauge length or by the total extension under load method using 0.5% of the gauge length.
Manufacture & Heat Treatment
The steel shall be made by either or both of the following processes: basic-oxygen or electric furnace. The steel may be cast in ingots or may be strand cast. In modern industry, ASTM A135 ERW steel pipes, either Grade A or Grade B, are generally made by a high-frequency electric-resistance welding process. The pipe shall be manufactured from flat rolled steel (plate) in individual lengths or in continuous length by electric-resistance or electric-induction welding without the addition of extraneous material. In simple words, no filler metal is required. The weld seam of ERW pipe to ASTM A135 Grade B shall be heat treated after welding to a minimum temperature of 1000°F [540°C] or processed in such a manner that no untempered martensite remains.
Surface Appearance & End Preparation
The ASTM A135 ERW steel pipes shall be reasonably straight and free of defects. Surface imperfections in excess of 12.5% of the nominal wall thickness shall be avoided. The pipes may be furnished with plain end, beveled end, or threaded end. Especially, ERW pipes furnished to SCH 10 shall be plain end only. All inside and outside cutting burrs shall be removed. Each length of threaded pipe shall be provided with one coupling for connection purpose.
Inspection & Test
Strict quality control shall be implemented to ensure the good quality of ASTM A135 ERW steel pipes. This includes chemical analysis of each heat lot, tension test, dimensional inspection, visual examination, hydrostatic test, flattening test, or non-destructive test (NDT) when required by the purchaser.
