Understanding API 5L X52 Specifications and Applications
API 5L X52 represents a specific steel grade within the API 5L standard, which outlines the production of two distinct product quality levels (PSL1 and PSL2) for line pipes. These pipes can be manufactured either as seamless or welded and are extensively utilized in the transportation of oil and natural gas across various regions worldwide. Our company, CSC, provides an array of other steel grades suitable for similar purposes, including X42, X46, X52, X56, X60, X65, and X70 line pipes, ensuring a comprehensive range of options tailored to meet diverse needs.
Manufacturing Process
The raw materials required for producing these pipes—such as steel ingots, billets, slabs, coils, or plates—are typically processed using methods like alkaline oxygen, electric arc furnaces, or open-hearth furnaces, often complemented by a ladle refining process. For PSL2 specifications, the steel must be fully deoxidized and refined following strict fine grain practices. Additionally, coils or sheets intended for PSL2 line pipes must be free from any repair welds to maintain their integrity.
In terms of welding techniques, API 5L X52 line pipes can be joined using three primary methods: ERW (Electric Resistance Welding), LSAW (Longitudinal Submerged Arc Welding), and SSAW (Spiral Submerged Arc Welding).
Delivery Conditions
| PSL Level |
Delivery Condition |
Pipe Grade |
| PSL1 |
As-rolled, normalized, normalizing rolled, thermomechanically rolled, thermomechanically formed, normalizing formed, normalized, normalized and tempered, or quench and tempered (Q&T) for seamless only |
A, B, X42, X46, X52, X56, X60, X65, X70 |
| PSL2 |
As-rolled, normalized rolled, normalized formed, normalized, normalized and tempered, quench and tempered, thermomechanically rolled, or thermomechanically formed |
BR, X42R, BN, X42N, X46N, X52N, X56N, X60N, BQ, X42Q, X46Q, X56Q, X60Q, X65Q, X70Q, X80Q, X90Q, X100Q, BM, X42M, X46M, X56M, X60M, X65M, X70M, X80M, X90M, X100M, X120M |
Chemical Composition for PSL 1 Pipe (t ≤ 0.984")
| Steel Grade |
Mass Fraction (%) Based on Heat and Product Analyses |
| C |
Mn |
P |
S |
V |
Nb |
Ti |
| Max |
Max |
Max |
Max |
Max |
Max |
Max |
| Seamless Pipe |
| X52 |
0.28 |
1.4 |
0.3 |
0.3 |
D |
D |
D |
| Welded Pipe |
| X52 |
0.26 |
1.4 |
0.3 |
0.3 |
D |
D |
D |
Chemical Composition for PSL 2 Pipe (t ≤ 0.984")
| Steel Grade |
Mass Fraction (%) Based on Heat and Product Analyses |
Carbon Equivalent (CE) |
| C |
Si |
Mn |
P |
S |
V |
Nb |
Ti |
Other |
CE IIW |
CE Pcm |
| Max |
Max |
Max |
Max |
Max |
Max |
Max |
Max |
Max |
Max |
| Seamless and Welded Pipe |
| X52N |
0.24 |
0.45 |
1.4 |
0.025 |
0.015 |
0.1 |
0.05 |
0.04 |
D,E,L |
0.043 |
0.25 |
| X52Q |
0.18 |
0.45 |
1.5 |
0.025 |
0.015 |
0.05 |
0.05 |
0.04 |
E,L |
0.043 |
0.25 |
| Welded Pipe |
| X52M |
0.22 |
0.45 |
1.4 |
0.025 |
0.015 |
D |
D |
D |
E,L |
0.043 |
0.25 |
a. For seamless pipes with wall thickness > 0.787", CE limits shall be agreed upon. CE IIW limits apply when C > 0.12%, while CE Pcm limits apply when C ≤ 0.12%.
b. For each 0.01% decrease in carbon below the specified maximum and each 0.05% increase in manganese above the specified maximum (up to a maximum of 1.65% for grades ≥ B but ≤ X52; 1.75% for grades > X52 but < X70; and 2.00% for X70).
c. Unless otherwise agreed, Nb = V ≤ 0.06%.
d. Nb = V = Ti ≤ 0.15%.
e. Unless otherwise agreed, Cu ≤ 0.50%; Ni ≤ 0.30%; Cr ≤ 0.30%; Mo ≤ 0.15%.
f. Unless otherwise agreed, Cu ≤ 0.50%; Ni ≤ 1.00%; Cr ≤ 0.50%; Mo ≤ 0.50%.
g. Unless otherwise agreed, Cu ≤ 0.50%; Ni ≤ 1.00%; Cr ≤ 0.55%; Mo ≤ 0.80%.
h. Unless otherwise agreed, Cu ≤ 0.50%; Ni ≤ 1.00%; Cr ≤ 0.55%; Mo ≤ 0.80%.
i. B ≤ 0.004%.
j. Unless otherwise agreed, Cu ≤ 0.50%; Ni ≤ 1.00%; Cr ≤ 0.55%; Mo ≤ 0.80%.
k. For all PSL 2 pipe grades except those noted with footnote j, no intentional addition of boron is allowed, and residual boron ≤ 0.001%. |
Mechanical Properties
| Pipe Grade |
Tensile Properties - Pipe Body of Seamless and Welded Pipes (PSL 1) |
Weld Seam of Welded Pipes |
| Yield Strength (Rt0,5) PSI Min |
Tensile Strength (Rm) PSI Min |
Elongation (% min) |
Tensile Strength (Rm) PSI Min |
| X52 |
52,200 |
66,700 |
- |
66,700 |
Hydrostatic Test
Pipes must withstand a hydrostatic pressure test without any leakage occurring at the weld seam or the pipe body. If the pipe sections used have been successfully tested, jointers do not require individual hydrostatic testing.
Bend Test
No cracks should appear in any part of the test specimen, and the weld must not open during the bend test.
Flattening Test
For EW pipes with D < 12.750 inches and T ≤ 500 inches, there should be no opening of the weld before the distance between the plates becomes less than 66% of the original outer diameter for X60 grade and 50% for all other grades and wall thicknesses. For pipes where D/t > 10, the weld should remain intact until the distance between the plates reaches less than 30% of the original outer diameter. Other size specifications can be found in the complete API 5L document.
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