ASTM A335 Steel Pipe

ASTM A335 Steel Pipe Description

ASTM A335 Standard‌ covers seamless alloy steel pipes primarily used in high-temperature, high-pressure piping systems. Compared to standard carbon steel pipes, ASTM A335 seamless pipes, made of alloy steel, offer higher strength and superior heat resistance. High-pressure pipelines operate under significant internal pressure and elevated temperatures, demanding materials with excellent strength, toughness, and corrosion resistance. ASTM A335 seamless pipes effectively meet these requirements, ensuring safe pipeline operation.

ASTM A335 seamless pipes exhibit excellent high-temperature performance. At elevated temperatures, steel's strength and toughness tend to degrade. However, various alloy steel grades under the ASTM A335 standard, such as P11, P22, and P91, are designed with special alloy elements and heat treatment processes, maintaining good mechanical properties at temperatures above 400°C. This is particularly crucial for high-temperature, high-pressure piping systems in thermal power plants and petrochemical facilities, extending pipeline lifespan and reducing maintenance frequency.

 

A335 Seamless Ferritic Alloy-Steel Pipe Specification

Heat Treatment Requirements of Alloy Steel Seamless Pipes

	P5, P9, P11 and P22
Grade	Heat Treatment Type	Normalizing Temperature Range F [C]	Subcritical Annealing or Tempering Temperature Range F [C]
P5 (b,c)	Full or isothermal Anneal
	Normalize and Temper	*****	1250 [675]
	Subcritical Anneal (P5c only)	*****	1325 - 1375 [715 - 745]
P9	Full or isothermal Anneal
	Normalize and Temper	*****	1250 [675]
P11	Full or isothermal Anneal
	Normalize and Temper	*****	1200 [650]
P22	Full or isothermal Anneal
	Normalize and Temper	*****	1250 [675]
P91	Normalize and Temper	1900-1975 [1040 - 1080]	1350-1470 [730 - 800]
	Quench and Temper	1900-1975 [1040 - 1080]	1350-1470 [730 - 800]

 

Chemical Requirements of Alloy Steel Seamless Pipes

Grade		P-5	P-9	P-11	P-22	P-91	P-91 shall also include the following:
Element	UNS Designation	K41545	S50400	K11597	K21590	K91560
Carbon		0.15 max	0.15 max	0.05 - 0.15	0.05 - 0.15	0.08 - 0.12	V at 0.18 - 0.25
Manganese		0.30 - 0.60	0.30 - 0.60	0.30 - 0.60	0.30 - 0.60	0.30 - 0.60	N at 0.030 - 0.070
Phosphorous, max		0.025	0.025	0.025	0.025	0.020	Ni at 0.40 max
Sulfur, max		0.025	0.025	0.025	0.025	0.010	Al at 0.02 max
Silicon		0.50 max	0.25 - 1.00	0.50 - 1.00	0.50 max	0.20 -0.50	Cb at 0.06 - 0.10
Chromium		4.00 - 6.00	8.00 - 10.00	1.00 - 1.50	1.90 - 2.60	8.00 - 9.50	Ti at 0.01 max
Molybdenum		0.45 -0.65	0.90 - 1.10	0.44 - 0.65	0.87 - 1.13	0.85 - 1.05	Zr at 0.01 max

 

Tensile Requirements of Alloy Steel Seamless Pipes

	Seamless
	P-5	P-9	P-11	P-22	P-91	P91 shall not have a hardness not exceeding 250 HB/265 HV [25HRC].
Tensile Strength, min., psi
ksi	60	60	60	60	85
MPa	415	415	415	415	585
Yield Strength, min., psi
ksi	30	30	30	30	60
MPa	205	205	205	205	415

 

Test and inspection

‌Chemical Composition Analysis‌: The content of elements in the alloy tube is detected through spectral analysis or chemical titration to ensure compliance with standard requirements.

‌Mechanical Property Testing‌: Includes tensile tests, impact tests, and bend tests to evaluate the strength, toughness, and plasticity of the alloy tube.

‌Metallographic Examination‌: The microstructure of the alloy tube is observed under a metallographic microscope to check for defects such as cracks and inclusions.

‌Hardness Testing‌: Tools like Brinell hardness testers, Rockwell hardness testers, or Vickers hardness testers are used to measure the hardness value, assessing wear resistance and deformation resistance.

‌Eddy Current Testing (ET)‌: Detects surface and near-surface defects (e.g., cracks, slag inclusions) in the alloy tube using eddy current principles.

‌Radiographic Testing (RT)‌: Uses X-rays or gamma rays to penetrate the alloy tube and inspect internal defects like porosity or slag inclusions.

‌Ultrasonic Testing (UT)‌: Detects internal and surface defects by analyzing the propagation characteristics of ultrasonic waves in the alloy tube.

‌Magnetic Particle Testing (MT)‌: Uses magnetic particles to reveal surface and near-surface defects, suitable for ferromagnetic materials.

‌Corrosion Resistance Testing‌: Evaluates the alloy tube's corrosion resistance under specific conditions to assess its performance in different environments.

‌Dimensional and Visual Inspection‌: Checks if the dimensions meet standards and verifies a smooth surface free of cracks, rust, etc.

 

Packaging and shipping