Description

API 5L Grade B Steel Pipe belongs to pipeline steel pipe. API 5L is a set of specifications for pipeline steel pipes formulated by the American Petroleum Institute, and Gr.B is an important steel grade in this standard. API 5L Grade B Steel Pipe can be divided into seamless pipes and welded steel pipes according to different processes.

Features of API 5L Grade B Steel Pipe:

API 5L Grade B Steel Pipe is a medium-strength pipeline steel pipe conforming to the American Petroleum Institute (API) 5L standard. It features low-carbon manganese steel composition, seamless or welded construction (commonly seamless), and is suitable for oil and gas transportation. It has a yield strength ≥241 MPa, tensile strength 413–517 MPa, and Charpy impact energy ≥27 J at -20℃.

1. Steel Grade and Strength: Gr.B belongs to the conventional strength grade (not the high-strength X series) of API 5L, with a yield strength not less than 241 MPa (35 ksi), a tensile strength range of 413–517 MPa, carbon content ≤0.28%, and manganese 0.60–1.35%, balancing strength and weldability.

2. Structural Form: API 5L Grade B Steel Pipe can be seamless (SEW) or straight seam welded (ERW/SAW), but “Gr.B” itself does not specify the forming method; seamless pipes have no weld seams, resulting in uniform pressure distribution and superior resistance to stress corrosion, and are commonly used in high-pressure/critical sections; welded pipes are lower in cost and used in trunk lines.

3. Chemical Composition Control: API 5L Grade B Steel Pipe strictly limits sulfur (≤0.025%) and phosphorus (≤0.025%), and microalloying (Nb/V/Ti may be added) to refine the grain size, ensuring low-temperature toughness and resistance to HIC (hydrogen-induced cracking).

4. Mechanical Properties: Elongation ≥21%, impact energy at -20℃ ≥27 J (standard requirement), which can be extended to -45℃ or even -60℃ operating conditions through TMCP or Ni microalloying.

5. Applications and Advantages: API 5L Grade B Steel Pipe is widely used in onshore and offshore oil and gas gathering and transportation, urban pipeline networks, and pressure systems below Class 300. Seamless Gr.B eliminates weak points in the weld, making it suitable for high pressure (4–12 MPa), corrosive environments, or complex terrain. Welded Gr.B is used for long-distance trunk lines.

6. Standards: Based on API SPEC 5L (45th edition and above), including PSL1 (basic) and PSL2 (additional performance, such as impact and UT testing); requires hydraulic pressure testing (≥1.5 × design pressure) and UT/RT non-destructive testing.

Note: “Gr.B” refers only to the steel grade and does not automatically represent “seamless”—actual products must be clearly marked “seamless” or “ERW/SAW”; high-strength steel (such as X60 and above) is used for trunk lines, while Gr.B is mostly used for branch lines, gathering and transportation, or non-extreme operating conditions.

Applications of API 5L Grade B Steel Pipe:

API 5L Grade B steel pipes are primarily used for long-distance transportation of fluids such as oil, natural gas, and water. They are suitable for onshore/submarine oil and gas trunk lines, urban gas pipelines, and medium-pressure fluid transportation systems in petrochemical plants.

1. API 5L Grade B Steel Pipes are widely used in long-distance onshore oil and gas pipelines (such as the West-East Gas Pipeline branch line and sections of the China-Russia East Route pipeline), urban gas distribution networks, oilfield gathering and transportation pipelines, and seawater/freshwater transportation projects.

2. They can be seamless steel pipes (hot-rolled/cold-drawn) or welded steel pipes (ERW/SAW). Seamless structures are more suitable for high-pressure/corrosive environments, while welded pipes are mostly used for medium- and low-pressure trunk lines.

3. API 5L Grade B Steel Pipes are also used for some industrial fluid transportation, heating networks, piling casings, and low-pressure structural applications, but their core application remains energy transmission trunk/secondary trunk lines.

API 5L Steel Pipe standard, the purpose of formulating this standard is to provide an applicable standard for pipes used for gas, water and oil transportation in the petroleum and natural gas industry. This standard applies to seamless steel pipes and welded steel pipes, including pipes with ordinary ports, threaded ports, socket ports, straight flow lines (TFL) and pipes with ports that have been processed for special connections.

API 5L standard specifies two product specification grades (PSLI and PSL2). The standard technical requirements specified for these two PSL grades are different. PSL2 has mandatory requirements for carbon equivalent, notch toughness, yield strength and tensile strength. The differences described here and other aspects are discussed in Appendix J. It can be clearly required to supply only PSL1 or PSL2 grades. If there is no clear requirement, one of them will be selected for supply. Whether ordering PSLI or PSL2 grade products, the purchaser can also add additional requirements. This standard has supplementary requirements (Appendix F) and other optional items.

The main steel grades of API 5L pipeline steel pipes are: A, B, X42, X46, X52, X56, X60, X65, X70, X80, X90, X100, X120, etc. Steel pipes of different steel grades have different manufacturing processes, different chemical compositions, different physical properties, different inspection methods, etc.

Specifications of Pipeline Steel Pipe:

Standard	Product Level	Steel grade	Yield Strength (min), Mpa	Tensile Strength（MPa）
API 5L GB/T9711.2	PSL 1	A or L210	210	335
		B or L245	245	415
		x42 or L290	290	415
		X46 or L320	320	435
		X52 or L360	360	460
		X56 or L390	390	490
		X60 or L415	415	520
		X70	483	565
	PSL 2	BR or L245R	245~450	415~760
		X42R or L290R	290~495	415~760
		BN or L245N	245~450	415~760
		X42N or L290N	290~495	415~760
		X46N or L320N	320~525	435~760
		X52N or L360N	360~530	460~760
		X56N or L390N	390~545	490~760
		X60N or L415N	415~565	520~760
		X65N or L450N	425~566	525~760
		X70 or L480	484~565	565~768
		X80	552~690	621~827

oduct Level	Steel grade	Chemical composition, %
oduct Level	Steel grade	C	Mn	P	S	Si	V	Nb	Ti	CEpcm
PSL 1	B or L245	≤0.28	≤1.20	≤0.030	≤0.030	–	–	–	–	–
	x42 or L290	≤0.28	≤1.30	≤0.030	≤0.030	–	–	–	–	–
	X46 or L320	≤0.28	≤1.40	≤0.030	≤0.030	–	–	–	–	–
	X52 or L360	≤0.28	≤1.40	≤0.030	≤0.030	–	–	–	–	–
	X56 or L390	≤0.28	≤1.40	≤0.030	≤0.030	–	–	–	–	–
	X60 or L415	≤0.28	≤1.40	≤0.030	≤0.030	–	–	–	–	–
	X70	≤0.28	≤1.40	≤0.030	≤0.030	–	–	–	–	–
PSL 2	BR or L245R	≤0.24	≤1.20	≤0.025	≤0.015	≤0.40	c	c	≤0.04	≤0.25
	X42R or L290R	≤0.24	≤1.20	≤0.025	≤0.015	≤0.40	≤0.06	≤0.05	≤0.04	≤0.25
	BN or L245N	≤0.24	≤1.20	≤0.025	≤0.015	≤0.40	c	c	≤0.04	≤0.25
	X42N or L290N	≤0.24	≤1.30	≤0.025	≤0.015	≤0.40	≤0.06	≤0.05	≤0.04	≤0.25
	X46N or L320N	≤0.24	≤1.40	≤0.025	≤0.015	≤0.40	≤0.07	≤0.05	≤0.04	≤0.25
	X52N or L360N	≤0.24	≤1.40	≤0.025	≤0.015	≤0.45	≤0.10	≤0.05	≤0.04	≤0.25
	X56N or L390N	≤0.24	≤1.40	≤0.025	≤0.015	≤0.45	≤0.10	≤0.05	≤0.04	≤0.25
	X60N or L415N	≤0.24	≤1.40	≤0.025	≤0.015	≤0.45	≤0.10	≤0.05	≤0.04	–
	X65N or L450N	≤0.24	≤1.40	≤0.025	≤0.015	≤0.45	≤0.10	≤0.05	≤0.04	–
	X70N	≤0.24	≤1.40	≤0.025	≤0.015	≤0.45	≤0.10	≤0.05	≤0.04	–
	X80	≤0.24	≤1.40	≤0.025	≤0.015	≤0.45	≤0.10	≤0.05	≤0.04	–