ASTM A335 P5, also known as ASME SA335 P5, is a low-alloy seamless steel pipe designed for high-temperature service.
P5 contains 4.00 ~ 6.00 % chromium and 0.45 ~ 0.65% molybdenum, offering excellent strength and performance under elevated temperatures and pressures. It is widely used in equipment such as boilers, superheaters, and heat exchangers.
Its UNS designation is K41545.
Manufacturer and Condition
ASTM A335 P5 steel pipes shall be made by the seamless process and shall be either hot finished or cold drawn, as specified.
Hot-finished pipes are seamless steel pipes manufactured from billets through heating and rolling processes, while cold-drawn pipes are seamless steel pipes produced by drawing hot-finished pipes at room temperature.
If you would like to learn more about the manufacturing processes of these two types of seamless steel pipes, you may click “What is Seamless Steel Pipe?” for further details.
Heat Treatment
ASTM A335 P5 pipes shall be reheated for heat treatment and heat treated by full or isothermal annealing or normalizing and tempering.
The specific requirements are shown in the table below:
| Grade | Heat treat type | Subcritical Annealing or Temperature |
| ASTM A335 P5 | full or isothermal anneal | — |
| normalize and temper | 1250 ℉ [675 ℃] min |
Operations that involve heating the steel pipes above their critical temperature, such as welding, flanging, and hot bending, should be followed by appropriate heat treatment.
The testing methods for the chemical composition and mechanical properties of P5 steel pipes shall comply with the relevant provisions of ASTM A999.
| Grade | Composition, % | ||||||
| C | Mn | P | S | Si | Cr | Mo | |
| P5 | 0.15 max | 0.30 ~ 0.60 | 0.025 max | 0.025 max | 0.50 max | 4.00 ~ 6.00 | 0.45 ~ 0.65 |
Tensile Properties
| Grade | Tensile Strength | Yield Strength | Elongation in 2 in. or 50 mm |
| P5 | 60 ksi [415 MPa] min | 30 ksi [205 MPa] min | 30 % min |
Hardness Properties
The ASTM A335 standard does not specify any hardness requirements for P5 steel pipes.
Flattening Test
Flattening test shall be conducted and sampled in accordance with the relevant requirements of ASTM A999, and cropped pipe ends may be used as specimens.
Bend Test
For pipe whose diameter exceeds NPS 25 and whose diameter to wall thickness ratio is 7.0 or less shall be subjected to the bend test instead of the flattening test.
The bend test specimens shall be bent at room temperature through 180° without cracking on the outside of the bent portion. The inside diameter of the bend shall be 1 in. [25 mm].
Appearance
The surface of the steel pipe shall be smooth and even, free from scabs, seams, laps, tears, or slivers.
If the depth of any defect exceeds 12.5% of the nominal wall thickness or if the remaining wall thickness is below the minimum specified thickness, the area shall be considered defective.
When the remaining wall thickness is still within the specified limits, the defect may be removed by grinding.
If the remaining wall thickness is below the minimum requirement, the defect shall be repaired by welding or removed by cutting.
Diameter Tolerance
For pipes ordered by NPS [DN] or outside diameter, variations in outside diameter shall not exceed the requirements shown in the table below:
| NPS [DN] Designator | Permissible Variations | |
| in. | mm | |
| 1/8 to 1 1/2 [6 to 40], inch. | ±1/64 [0.015] | ±0.40 |
| Over 1 1/2 to 4 [40 to 100], inch. | ±1/32 [0.031] | ±0.79 |
| Over 4 to 8 [100 to 200], inch. | -1/32 - +1/16 [-0.031 - +0.062] | -0.79 - +1.59 |
| Over 8 to 12 [200 to 300], inch. | -1/32 - +3/32 [-0.031 - 0.093] | -0.79 - +2.38 |
| Over 12 [300] | ±1 % of specified outside diameter | |
For pipe ordered to inside diameter, the inside diameter shall not vary more than 1% from the specified inside diameter.
Wall Thickness Tolerances
In addition to the implicit limitation of wall thickness for pipe imposed by the limitation on weight in ASTM A999, the wall thickness for pipe at any point shall be within the tolerances specified in the table below:
| NPS [DN] Designator | Tolerance, % form Specified |
| 1/8 to 2 1/2 [6 to 65] incl. all t/D ratios | -12.5 - +20.0 |
| Above 2 1/2 [65], t/D ≤ 5% | -12.5 - +22.5 |
| Above 2 1/2, t/D ＞ 5% | -12.5 - +15.0 |
| t = Specified Wall Thickness; D = Specified Outside Diameter. | |
ASTM A335 P5 steel pipes are primarily used in piping systems operating under high-temperature and high-pressure conditions.
Due to their excellent high-temperature resistance and mechanical properties, they are widely utilized in the petrochemical, power generation, and refinery industries.
Specific applications include:
- Boiler piping
- Heat exchangers
- Petrochemical process lines
- Power plant piping
- Boiler pressure vessels
| ASME | ASTM | EN | JIS |
| ASME SA335 P5 | ASTM A213 T5 | EN 10216-2 X11CrMo5+I | JIS G 3458 STPA25 |
Material: ASTM A335 P5 seamless steel pipes and fittings;
Size: 1/8" to 24", or customized according to your requirements;
Length: Random length or cut to order;
Packaging: Black coating, beveled ends, pipe end protectors, wooden crates, etc.
Support: IBR certification, TPI inspection, MTC, cutting, processing, and customization;
MOQ: 1 m;
Payment Terms: T/T or L/C;
Price: Contact us for the latest T11 steel pipe prices.
