Overview

ASTM A335 P91 is a superalloy steel, which is a low-alloy chromium molybdenum steel. It is widely used in pipelines and equipment under high temperature and pressure environment, such as petrochemical, electric power, nuclear power plant and other fields. The main components of the material are chromium, molybdenum, copper, manganese, silicon, phosphorus, sulfur and other elements, among which the content of chromium and molybdenum is relatively high, which can improve the high temperature resistance and oxidation resistance of the material.

Chrome Moly Pipe – ASTM A335 Pipe

ASTM A335 / ASME SA335 Pipe named chrome moly pipe as they have a high level of Chromium and Molybdenum.
Chromium will increase oxidation resistance and provides high-temperature strength, along with the better tensile & yield strength and proper hardness at room temperature. When the chromium content increased more than 12%, it can be classified as stainless steel.
Molybdenum increases the overall strength, resistance, elasticity, hardenability and overall quality, moly ensures that the material is more resistant to softening, restrains the growth of grains and lessens the chances of embrittlement. It is the single additive that is responsible for the increase in high temperature resistance (to 540-750°C) and it also improves the corrosion resistance to steel.

Elongation

Elongation in 2 in or 50mm or 4D minimum%

For wall thickness 5/16 in [8mm] and over

Longitudinal 30% and Transverse 20%

Elongation smaller 2 in or 50mm or 4D minimum%

For wall thickness 5/16 in [8mm] and over

Longitudinal 22% and Transverse 14%

For strip tests a deduction of each 0.8mm below 8mm shall be calculated with the Table 5 in ASTM A335

Chemical Composition

Mechanical Properties

Heat Treatment

ASTM A335 P91 shall be heat treated with normalize and temper, or quench and temper, normalize temperature 1900-1975℉ [1040-1080℃], subcritical annealing or tempering temperature minimum or range 1350-1470 ℉ [730-800℃].

Application

Power generation

Gas processing equipment

Oil services

Petrochemical plants

Heaters/reheat lines

Boilers

Test

Tensile tests: Transverse and Longitudinal
Flattening test
Hardness test not exceeding 250 HBW/265 HV30 [25HRC]
Bend Test shall be carried as per ASTM A370
Hydrostatic Test shall be carried , depending on the buyer a nondestructive examination shall be performed plus with hydrostatic test.

Package Process

1.with plastic cap to protect both ends

2.weaving bag wrapped outside the pipe

3.then pack into wooden case.

Image

Company introduction