B7 Alloy Steel Bolting for Oil & Gas Applications
API 20E BSL-2 ASTM A193 Grade B7 stud bolts are designed for critical bolted joints used in the oil & gas, petrochemical, refinery, and power generation industries. Manufactured in accordance with API Specification 20E at Bolting Specification Level 2 (BSL-2), these stud bolts provide enhanced manufacturing control, mechanical reliability, and full traceability, more strict than ASTM requirements.
A193 B7 stud bolts qualified to API 20E BSL-2 are widely specified for pressure-containing flanged joints for Oil& gas applications.
What Is API 20E BSL-2?
API Specification 20E defines requirements for the qualification, production, testing, and documentation of metallic bolting used in the petroleum and natural gas industry.
It introduces Bolting Specification Levels (BSL-1, BSL-2, BSL-3) to ensure the appropriate level of quality assurance for different service criticalities.
BSL-2 is specified for critical service bolting, providing a higher level of control than standard ASTM fasteners.
API 20E BSL-2 Key Requirements
- Qualified manufacturing procedure
- Heat treatment procedure qualification
- Increased mechanical testing frequency
- Lot-by-lot traceability
- Documented process control from raw material to finished stud bolt
Stud Bolt Material: ASTM A193 Grade B7
ASTM A193 Grade B7 is a chromium-molybdenum alloy steel, quenched and tempered to achieve high strength for high-temperature and high-pressure service.
Key Properties of A193 B7 Stud Bolts
- High tensile and yield strength
- Reliable performance up to ~450 °C
- Excellent load-carrying capability
- Industry-standard bolting material for ASME flanges
Product Description
- Product: Stud Bolt
- Standard: ASTM A193 Grade B7
- API Compliance: API 20E BSL-2
- Thread Type: UNC / UNF / 8UN
- Finish: Plain, black, or coated (Xylan®, PTFE, etc.)
- Matching Nuts: ASTM A194 Grade 2H
Size Range
- Diameter: 1/4″ – 4″
- Length: As per ASME flange standards or customer drawings
ASTM A193 B7 Compsition
ASTM A193 B7 (Cr-Mo AISI 4140,4142,4145)
This material is considered as the most suitable for bolts to be used at temperature below 450 °. C, with
a minimum effect on its structural strength during application at a high temperature.
The material has the following chemical properties and physical Characteristics.
| C | Mn | P | S | Si | Cr | Mo |
|---|---|---|---|---|---|---|
| 0.37-0.49 | 0.65-1.10 | 0.035 Max | 0.04 Max | 0.15-0.35 | 0.75-1.20 | 0.15-0.25 |
Mechanical Properties – ASTM A193 B7
| Diameter, inch. | Tensile Strength, min, ksi | Yield Strength, min, 0.2% offset, ksi | Elongation in 4D, min, % | Reduction of Area, min, % | Hardness, max |
| 2-1/2 and under | 125 | 105 | 16 | 50 | 321 HBW or 35 HRC |
| over 2-1/2 to 4, inclusive | 115 | 95 | 16 | 50 | 321 HBW or 35 HRC |
| over 4 to 7, inclusive | 100 | 75 | 18 | 50 | 321 HBW or 35 HRC |
Heat Treatment
API 20E BSL-2 A193 B7 stud bolts are supplied in the quenched and tempered condition, with heat treatment fully qualified and documented per API 20E requirements.
Testing & Inspection (API 20E BSL-2)
- Chemical analysis
- Tensile testing
- Hardness testing
- Dimensional inspection
- Visual inspection
- Heat treatment verification
- Full traceability documentation
- Certification: API 20E BSL-2 + EN 10204 3.1 / 3.2
API 20E BSL-2 ASTM A193 B7 stud bolts deliver superior reliability, traceability, and mechanical performance for critical oil & gas and pressure equipment applications. Fully compliant with API 20E BSL-2 requirements, these stud bolts are the preferred fastening solution where safety, quality assurance, and long-term integrity are mandatory.
