Mechanical Properties Terms for Seamless Pipe

by Jane Tian on Sep 24, 2025 Business 46 Views

Index analysis of mechanical properties of seamless pipes (smls pipe):

1. The performance index analysis of seamless pipe--plasticity.

Plasticity refers to the ability of metal materials to produce plastic deformation without being damaged under load.

2. Analysis of performance index of seamless pipe--hardness.  

Hardness is a measure of the hardness of metal materials. At present, the commonly used method for measuring hardness in production is the indentation hardness method, which uses a certain geometric indenter to press into the surface of the metal material to be tested under a certain load, and the hardness value is determined according to the degree of indentation. Commonly used methods are Brinell hardness (HB), Rockwell hardness (HRA, HRB, HRC) and Vickers hardness (HV) and other methods.

3. The performance index analysis of seamless pipe--fatigue.
The strength, plasticity, and hardness discussed above are all indicators of the mechanical properties of metals under static load. In fact, many machine parts are working under cyclic loads, under which conditions the parts will fatigue.

4. Seamless performance index analysis--impact toughness.  

The load acting on the machine at a very large speed is called impact load, and the ability of metal to resist damage under impact load is called impact toughness.

5. Analysis of the performance index of seamless pipes--strength.  

Strength refers to the ability of metal materials to resist damage (excessive plastic deformation or fracture) under static load. Since the load acts in the form of tension, compression, bending, shearing, etc., the strength is also divided into tensile strength, compressive strength, flexural strength, and shear strength. There is often a certain connection between various strengths, and tensile strength is generally used as the basic strength indicator in use.

How to determine the mechanical properties requirements of seamless pipes?

Step 1: First understand the "working conditions" - determine the performance level

Working condition characteristics

Key mechanical concerns

Examples

Normal temperature and low pressure fluid

Yield, elongation

Water and air pipes

Low temperature environment (≤-20°C)

Low temperature impact toughness KV2

LNG pipelines

High-pressure boiler/steam

High temperature yield and endurance strength

Main steam pipe 600 ℃

Dynamic load, fatigue

Impact energy, fatigue limit

Marine and wind turbine towers

Corrosion with H₂S/CO₂

Upper limit of SSC resistance hardness

Oil and gas well casing

 

Step 2: Lock in the "product standard" - the standard gives all mechanical indicators at one time

Use

Implementation Standards (Latest Version)

Mandatory mechanics items

High-pressure boiler

GB/T 5310-2025

Rm, ReL, A, KV2, hardness, endurance strength

Petrochemicals

GB/T 9948-2025

Rm, ReL, A, KV2, hardness, grain size

Structural pipes

GB/T 8162-2018

Rm, ReL, A, flattening, flaring

Cryogenic fluid

GB/T 6479-2013

Rm, ReL, A, KV2 (-20 ℃/-40 ℃)

Oil casing pipe

API 5CT 11th Edition

Rm, ReL, A, hardness, impact (SR16)

 

Step 3: Extract “quantitative indicators” – convert standard clauses into tables

Take 15CrMoG (GB/T 5310-2025) for high-pressure boilers as an example:

Index

Required value

Test temperature

Tensile strength Rm

440-640 MPa

Room temperature

Yield strength ReL

≥235 MPa

Room temperature

Elongation A

≥21 %

Room temperature

Impact absorption energy KV2

≥40 J

20 ℃

Hardness HBW

135-195

Room temperature

600 ℃ 10⁵ h rupture strength

≥100 MPa

600 ℃

 

Step 4: Clarify the “test method” – ensure data traceability

Pilot projects

Method standards

Sampling location

Remark

Stretch

GB/T 228.1-2021

1 set each vertically and horizontally

Gauge length 50 mm

Impact

GB/T 229-2020

Vertical V-notch

Low temperature requires keeping warm for ≥10 min

Hardness

GB/T 231.1-2018

Three-point average of the outer surface

Avoid welds

Flattening/flaring

GB/T 246-2017

Pipe end 100 mm

Structural pipe must be done

Lasting strength

GB/T 2039-2021

3 pieces from the same batch

High temperature long time test


Step 5: Add a “verification clause” to the contract

Certificate: EN 10204 3.1/3.2 or GB/T 247 quality assurance certificate.

Lossless: UT (GB/T 5777 C5), ET (GB/T 7735 Class A).

Re-examination: If any indicator fails, double sampling will be conducted for re-examination. If it fails again, the entire batch will be scrapped.

Identification: Spray code "furnace batch number + standard number + impact temperature" for easy traceability.

Article source: https://article-realm.com/article/Business/77518-Mechanical-Properties-Terms-for-Seamless-Pipe.html

URL

https://www.permanentsteel.com/productshow/seamless-steel-pipe.html
Permanent Steel Manufacturing Co.,Ltd have years of experience in manufacturing of carbon steel pipe, stainless steel tube, hollow section, pipe fittings.(Fluid Pipe/Boiler Tube/Fire Pipe/Line Pipe/Structure Tube) Please refer to: https://www.permanentsteel.com

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