ASTM A335 Pipe

ASTM A335 pipe are classified as chrome moly pipe. Chrome Moly Alloy Steel pipe has high Tensile Strength, Corrosion resistance and has High Temperature Strength so it majorly used in Power Generation Industries and Petro Chemical industries. Chrome Moly is derived from Chromium -Molybdenum, which is also, know as Cr-Mo Steel Pipe. This pipe are Intended for High Temperature and high Pressure Service. Chrome-Moly Alloy Steel pipe has a better strength to Weight ratio than Other steel, which enables us to use thinner wall pipe or smaller diameter pipe to reduce overall weight. Chrome Moly pipe are also known as Alloy pipe

General Abbreviations of chrome moly pipe are chrome-moly, cro-moly, CrMo, CRMO, CR-MOLY.

As a result, The chrome moly pipe finds high usage in power generation industry and petrochemical industry owing to its resistance to corrosion, tensile strength, strength for high temperature owing to its cost-effectiveness.

Size range:

• NPS 1/4” to NPS 24”
• Wall Thickness – Schedules 40 through 160, STD, XS, XXS.
• Unscheduled heavy wall pipe thicknesses available up to 4 inches.

Pipe ordered to this specification shall be suitable for bending, flanging (vanstoning), and similar forming operations, and for fusion welding. Sometimes referred to as “P Grade”, chome moly pipe is popular in P-Grades P5, P9, P11, P22, and P91.

ASTM A335 standard is issued under the fixed designation A 335/A 335M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision.

The most common use of grades P11, P22, and P91 is in the power industry and petro-chemical plants, Grades P5 and P9 are commonly used in refineries.

ASTM A335 is often called as chrome moly pipe because of the chemical contain of Molybdenum (Mo) and Chromium (Cr). Molybdenum increases the strength of steel and Chromium (or chrome) is the essential constituent of stainless steel.

The composition chrome moly alloy steel pipe make it ideal for use in power plants, refineries, petro chemical plants, and oil field services where fluids and gases are transported at extremely high temperatures and pressures.

Certitifcation: Chrome Moly pipe are certified as PER DIN 50049 3.1, EN 10204 3.1/3.2 and NACE MR-0175 & NACE MR-0103

Piping Component Specifications:

• Flanges and forged fittings – A/SA 182 F1, F2, F5, F9, F11, F12, F15, F22, F91, F92, F122 Wrought
• Butt-weld Pipe Fittings – A/SA 234 P1, P2, P5, P9, P11, P12, P15, P22, P91, P92, P122

• Strong resistance to rupturing at high temperatures and high pressures.
• May be used for hydrogen sulfide corrosion services.
• Resistant to cracking from hydrogen attack and embrittlement.
• Resistant to hot sulfide corrosion cracking.
• Can be used for NACE applications where sour environments are under high temp and pressure.
• Can be used in NACE-MRO 175 sour service.
• Ideal for creep rupture applications.
• Can handle high temperatures with very low elasticity.

Chemical Composition(%) ASTM A335

ASTM Specification pipe confirming to ASTM A335 shall have the following chemical properties. Tensile and Hardness Requirements The tensile properties of the ASTM A335 pipe shall conform to the requirements as prescribed. Pipe of Grades P91, P92, and P122 shall have a hardness not exceeding 250 HB/265 HV [25 HRC]. For pipe of Grades P91, P92, P122, and P911, Brinell, Vickers, or Rockwell hardness tests shall be made on a specimen from each lot (see Note 7). These pipe bear high resistance to rupture at high temperature and pressures. With hydrogen crack resistance and sulfide stress corrosion cracking chrome moly pipe are highly preferred over Carbon pipe.

Grade	UN	C≤	Mn	P≤	S≤	Si≤	Cr	Mo
P1	K11522	0.10~0.20	0.30~0.80	0.025	0.025	0.10~0.50	–	0.44~0.65
P2	K11547	0.10~0.20	0.30~0.61	0.025	0.025	0.10~0.30	0.50~0.81	0.44~0.65
P5	K41545	0.15	0.30~0.60	0.025	0.025	0.5	4.00~6.00	0.44~0.65
P5b	K51545	0.15	0.30~0.60	0.025	0.025	1.00~2.00	4.00~6.00	0.44~0.65
P5c	K41245	0.12	0.30~0.60	0.025	0.025	0.5	4.00~6.00	0.44~0.65
P9	S50400	0.15	0.30~0.60	0.025	0.025	0.50~1.00	8.00~10.00	0.44~0.65
P11	K11597	0.05~0.15	0.30~0.61	0.025	0.025	0.50~1.00	1.00~1.50	0.44~0.65
P12	K11562	0.05~0.15	0.30~0.60	0.025	0.025	0.5	0.80~1.25	0.44~0.65
P15	K11578	0.05~0.15	0.30~0.60	0.025	0.025	1.15~1.65	–	0.44~0.65
P21	K31545	0.05~0.15	0.30~0.60	0.025	0.025	0.5	2.65~3.35	0.80~1.60
P22	K21590	0.05~0.15	0.30~0.60	0.025	0.025	0.5	1.90~2.60	0.87~1.13
P91	K91560	0.08~0.12	0.30~0.60	0.02	0.01	0.20~0.50	8.00~9.50	0.85~1.05
P92	K92460	0.07~0.13	0.30~0.60	0.02	0.01	0.5	8.50~9.50	0.30~0.60

Chrome Moly Pipes: Werkstoff vs EN vs ASTM

ASTM A335 pipe may be either hot finished or cold drawn with the finishing treatment as required in Grade P2 and P12 – The steel shall be made by coarse- grain melting practice. Specific limits, if any, on grain size or deoxidation practice shall be a matter of agreement between the manufacturer and purchaser.

Werkstoff /DIN	EN	ASTM
1.5415	16Mo3	A335 Grade P1
1.7335	13CrMo4-5	A335 Grade P11, P12
1.738	10CrMo9-10	A335 Grade P22
1.7362	X11CrMo5	A335 Grade P5
		A335 Grade P9
1.4903	X10CrMoVNb9-1	A335 Grade P91

Tensile Requirements

Tensile Strength, min., psi	P-5	P-9	P-11	P-22	P-91
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

Product Analysis At the request of the purchaser, an analysis of two pipe from each lot shall be made by the manufacturer. A lot of ASTM A335 pipe shall consist of the following: NPS Designator Under 2 400 or fraction thereof 2 to 5 200 or fraction thereof 6 and over 100 or fraction thereof.
Note: ASTM A335 P91 shall not have a hardness not exceeding 250 HB/265 HV [25HRC].

Mechanical properties of ASTM A335

Grade	Tensile strength	Yield strength
P1,P2	380	205
P12	415	220
P23	510	400
P91	585	415
P92,P11	620	440
P122	620	400

A335 is often called chrome moly pipe because of the chemical makeup of Molybdenum (Mo) and Chromium (Cr). Molybdenum increases the strength of steel as well as the elastic limit, resistance to wear, impact qualities, and hardenability. Moly increases the resistance to softening, restrains grain growth and makes chromium steel less susceptible to embrittlement. Moly is the most effective single additive that increases high temperature creep strength.

It also enhances the corrosion resistance of steel, and inhibits pitting. Chromium (or chrome) is the essential constituent of stainless steel. Any steel with 12% or more Chrome is considered stainless. Chrome is virtually irreplaceable in resisting oxidation at elevated temperatures. Chrome raises the tensile, yield, and hardness at room temperatures. The composition chrome moly alloy steel pipe make it ideal for use in power plants, refineries, petro chemical plants, and oil field services where fluids and gases are transported at extremely high temperatures and pressures.

Heat Treatment Requirements

Grade	Heat Treatment Type P5, P9, P11, and P22	Normalizing Temperature Range F [C]	Subcritical Annealing or Tempering Temperature Range F [C]
A335 P5 (b,c)	Full or Isothermal Anneal
	Normalize and Temper	*****	1250 [675]
	Subcritical Anneal (P5c only)	*****	1325 – 1375 [715 - 745]
A335 P9	Full or Isothermal Anneal
	Normalize and Temper	*****	1250 [675]
A335 P11	Full or Isothermal Anneal
	Normalize and Temper	*****	1200 [650]
A335 P22	Full or Isothermal Anneal
	Normalize and Temper	*****	1250 [675]
A335 P91	Normalize and Temper	1900-1975 [1040 - 1080]	1350-1470 [730 - 800]
	Quench and Temper	1900-1975 [1040 - 1080]	1350-1470 [730 - 800]

Permissible Variation in Wall Thickness

NPS [DN] Designator	Tolerance, % from Specified
	Over	Under
1/8 to 2 1/2 [6 to 65] incl., all t/D ratios	0.2	0.125
Above 2 1/2 [65], t/D < or = 5%	0.225	0.125
Above 2 1/2 [65], t/D > 5%	0.15	0.125

(t = Specified Wall Thickness; D = Specified Outside Diameter)

Mechanical Tests Specified
Transverse or Longitudinal Tension Test and Flattening Test, Hardness Test, or Bend Test
For material heat treated in a batch-type furnace, tests shall be made on 5% of the pipe from each treated lot. For small lots, at least one pipe shall be tested.
For material heat treated by the continuous process, tests shall be made on a sufficient number of pipe to constitute 5% of the lot, but in no case less than 2 pipe.

Notes for Hardness Test:
P91 shall not have a hardness not exceeding 250 HB/265 HV [25HRC].

Notes for 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.
Other pipe whose diameter equals or exceeds NPS 10 may be given the bend test in place of the flattening test subject to the approval of the purchaser.
The bend test specimens shall be bent at room temperature through 180 without cracking on the outside of the bent portion.

Hydrostatic Test
The inside diameter of the bend shall be 1 inch [25 mm].
Each length of pipe shall be Hydro tested, at option of manufacture nondestructive electric testing can be used.

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