|Alloy Or Not:||Is Alloy||Technique:||Hot Rolled|
|Application:||Structure Pipe||Section Shape:||Round|
|Usage:||Oil Gas Sewage Transport||Surface:||Customers't Requirement|
carbon steel seamless tube,
carbon steel seamless pipes
A335 P9 Alloy Steel Pipe ASTM A335/ASME SA335 Gr. P5, P9, P11, P22, P91
Standard: ASTM A335
Length:5.8m-12m or random legth
Technical: Quenching & Tempering
Application: Gas fire power plant, coal fire power plant, headers and steam lines, Feed water pipes,
super heaters and reheaters.
A335 P9 Alloy Steel Pipe that covers “chrome-moly” seamless pipes with remarkable resistance to
corrosion and good tensile strength at high-temperature service. Generally, ASTM A335 P11, P22,
and P91 pipes are used in power generation and in downstream oil and gas, P5 and P9 grades are
for refinery applications.
How to define alloy pipes?
Alloy pipes are tubular with higher percentages, than standard carbon steel pipes, of alloying elements
as Molybdenum (Mo), Chromium (Cr), Nickel, etc. Actually, the ASTM A335 covers “low-alloy” steel pipes,
i.e. pipes that have a total amount of alloying elements below 5%. The addition of higher percentages of
alloying elements (example Nickel and Chromium) transforms the steel into higher alloys, like stainless steel,
duplex, up to super-alloyed materials like Inconel, Hastelloy, Monel, etc.
Alloy steel pipes are used in the energy industry for high temperature and very low-temperature service
(cryogenic), or for applications with very high pressures.
ASTM A335 alloy steel pipes fit ASTM A234 WPx series buttweld fittings (WP5, WP9, WP91) and A182 Fx
forged fittings and flanges (A182 F5, F9, F11, F22, F91). All these materials have similar chemical and mechanical
properties and can be joined or welded.
The addition of Molybdenum (“Moly”) increases the strength of the steel and its elastic limit, enhance
the steel resistance to wear, its impact qualities, and the hardenability. It also improves the resistance
to softening, makes chromium steel less prone to embrittlement and prevents pitting.
Chromium, a key element also for stainless steel alloys, prevents steel oxidation at elevated temperatures
and increases the resistance of steel to corrosion. It enhances the tensile, yield, and hardness properties
of low-alloy pipes at room temperatures.
Other alloying elements, present in various degrees in pipes of all grades are:
1. Aluminum: decreases oxygen from steelmaking
2. Boron: used to produce fine grain size and enhance steel hardness
3. Cobalt: used to enhance the steel’s heat and wear-resistance
4. Manganese: gives better steel hardenability
5. Nickel: Enhances toughness, hardenability and impact strength at low temperatures
6. Silicon: decreases oxygen, enhances hardenability and toughness
7. Titanium: prevents precipitation of chromium carbide
8. Tungsten: refines steel grain size and enhance the steel hardness, especially at high temperatures
9. Vanadium: gives steel enhanced fatigue resistance
As mentioned, low-alloy steels have a total amount of alloying elements below 5%; high alloy steel has a higher
percentage of these elements.
A335 steel pipe Heat Treatment:
A335 pipes shall be reheated and furnished in the full-annealed, isothermal annealed,or normalized and tempered
condition. If furnished in the normalized and tempered condition, the minimum tempering temperature for Grades P5,
P5b, P9, P21, and P22 shall be1250°F [675°C], the minimum tempering temperature for Grades P1, P2, P11, P12,
and P 15 shall be 1200°F [650°C].
Pipe of Grades P1, P2, and P12, either hot finished or cold drawn, may be given a final heat treatment at 1200°F[650°C] to
1300°F [705°C] instead of heat treatments
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