ASME SA106 Gr.B Seamless Carbon Steel Pipe for High Temperature Service
ASME SA106 Gr.B Seamless Steel Pipe – Carbon Steel Pipe for High-Temperature Service
1. Standard Overview
SA106 Gr.B (also written as SA-106 Gr.B) is a seamless carbon steel pipe specified under ASME SA106 / ASTM A106 for high-temperature service, and it is the most widely used American standard seamless pipe in global energy and petrochemical industries.
The standard covers three grades: A, B and C. Gr.B delivers an optimal balance of strength, toughness and weldability, extensively applied for transporting high-temperature and high-pressure fluids. Distinct from line pipe API 5L Gr.B, SA106 Gr.B pipe is engineered specifically for boilers, steam systems and high-temperature process piping, with stricter requirements on high-temperature rupture properties, heat treatment and non-destructive testing.
2. Chemical Composition (Mass Fraction, %)
| Element | Specified Limit |
| C | ≤0.30 |
| Mn | 0.29～1.06 |
| Si | ≥0.10 |
| P | ≤0.035 |
| S | ≤0.035 |
| Cr, Ni, Cu | ≤0.40 |
| Mo | ≤0.15 |
| V | ≤0.08 |
Supplementary Note: The upper carbon limit ensures good weldability. Strict control of harmful impurities sulfur and phosphorus reduces the risk of high-temperature temper brittleness and crack formation.
3. Mechanical Properties (Minimum Values at Room Temperature)
Hardness Reference: Industry internal control reference limits: HRB ≤90 for pipes with outer diameter ≤50 mm; HB ≤187 for larger sizes. This hardness requirement is not mandatory under ASME SA-106. If hardness control is required for a project, it shall be separately agreed in the purchase contract.
Operating Temperature Range: In accordance with ASME B31.3, without additional Charpy impact testing, the normal operating temperature range is -29℃ ~ 454℃. Considering graphitization risk and creep characteristics of carbon steel at elevated temperatures, the recommended maximum temperature for long-term continuous service is 399℃ (750℉). The range of 425℃ ~ 454℃ is only suitable for intermittent and short-term operating conditions. It is well suited for pipelines conveying steam, high-temperature oil and gas.
4. Manufacturing Process & Size System
Manufacturing Method
Two production options: hot-finished seamless and cold-drawn (cold-rolled) seamless. Delivery conditions are normally hot-finished or normalized. Cold-drawn pipes feature higher dimensional accuracy and smoother inner surfaces, commonly used for heat exchanger tubes; hot-finished pipes are suitable for large-diameter and heavy-wall main piping.
Size Standard
Dimensions comply with ASME B36.10M, covering nominal sizes from 1/8" up to 48" and larger upon request. Wall thickness schedules include STD, XS, XXS as well as SCH10～SCH160. Cut-to-length and multiple-length pipes are available.
General Inspection Requirements
Each pipe shall undergo hydrostatic or air pressure test. Additional inspections such as UT ultrasonic testing, ET eddy current testing can be arranged upon request; alternative non-destructive testing methods may be adopted through mutual agreement. PMI positive material identification is available. Test certificates conforming to EN10204 3.1 / 3.2 can be provided.
As required by ASME SA-106, tensile tests shall be carried out on a batch basis. Flattening tests are required for sizes NPS 2 and above, while bend tests apply to pipes NPS 2 and below. Every pipe shall be subjected to hydrostatic test, or full-length eddy current testing may be used as an alternative upon mutual agreement. Charpy impact tests can be added in accordance with purchaser’s service requirements. Grain size measurement and other special examinations are additional contractual inspections to be agreed by both parties in advance.
5. Core Material Advantages
Excellent High-Temperature Mechanical Stability
Maintains stable strength within 400℃ and offers good thermal fatigue resistance, ideal for steam pipelines under cyclic start-stop operating conditions.
Superior Workability
Suitable for hot bending, cold bending, cutting and welding. Complex post-weld heat treatment is generally not required under normal service conditions, offering favorable weldability.
High Safety of Seamless Structure
Free of weld weak zones with uniform pressure-bearing capacity, lowering the risk of leakage for high-pressure media.
6. Typical Application Fields
Power Industry (Thermal Power & Cogeneration)
Boiler economizers, water walls, superheater piping, main steam pipelines, boiler feedwater lines, cooling pipelines for generator sets.
Petroleum & Petrochemical Industry
Heater piping in refineries, high-temperature hot oil pipelines, heat exchanger tubes, process oil & gas pipelines.
Chemical Industry
High-temperature process fluid pipelines, heat exchange equipment, connecting nozzles for medium and small pressure vessels.
General Industry
Thermal pipe networks, waste heat recovery systems, high-temperature hydraulic and thermal oil pipelines.
7. Summary
SA106 Gr.B seamless carbon steel pipe features well-balanced strength, heat resistance and weldability, making it a classic material for high-temperature and high-pressure industrial pipelines. It has achieved long-term stable service in thermal power and petrochemical projects. Safe long-term operation can be guaranteed provided production, inspection and installation specifications are strictly followed.