RapidBoltHigh Temperature Bolting for Turbines, HRSGs & Fired Heaters
Superalloys and specialised high-temperature steels engineered to maintain strength, creep resistance, and oxidation resistance at sustained elevated temperatures.
Material Characteristics
High temperature alloy fasteners are essential for applications where service temperatures exceed the practical limits of standard carbon and alloy steels. These materials are specifically designed to resist creep, stress relaxation, and high-temperature oxidation over extended service periods.
Iron-based superalloys like ASTM A453 Grade 660 (A-286) provide a cost-effective solution for temperatures up to 704°C, while nickel-based superalloys such as Waspaloy and Nimonic extend the operating envelope to 870°C and beyond. The critical difference from standard alloy steels is that these materials maintain their bolt load over years of continuous high-temperature service.
EMG supplies high-temperature fasteners for power generation, refinery, and petrochemical applications with full EN 10204 3.1 certification. Our team provides expert guidance on material selection based on your specific temperature, environment, and stress requirements.
Key Properties
Available Grades & Specifications
We stock and supply the following grades. All materials supplied with EN 10204 3.1 mill test reports and full chemical and mechanical certification.
| Designation | Description |
|---|---|
| ASTM A193 B16 | Chrome-Moly-Vanadium Steel |
| ASTM A453 660 Cl.A | A-286 Iron-Based Superalloy |
| ASTM A453 660 Cl.B | A-286 Iron-Based Superalloy |
| ASTM A453 660 Cl.C | A-286 Iron-Based Superalloy |
| ASTM A453 660 Cl.D | A-286 Iron-Based Superalloy |
| Waspaloy (N07001) | Ni-Cr-Co-Mo Superalloy |
| Nimonic 80A (N07080) | Ni-Cr-Ti-Al Superalloy |
| Nimonic 90 (N07090) | Ni-Cr-Co Superalloy |
| Hastelloy C-276 (N10276) | Ni-Mo-Cr Universal Alloy |
| Incoloy 825 (N08825) | Ni-Fe-Cr-Mo-Cu Alloy |
| Durehete 1055 | 1CrMoV Bolting Steel |
| Durehete 950 | High-Temp Bolting Steel |
Typical Applications
- Steam turbine casing and flange bolting
- Gas turbine hot section fasteners
- HRSG (Heat Recovery Steam Generator) bolting
- Refinery heater tube hangers and supports
- Boiler drum and header connections
- Exhaust manifold and turbocharger fasteners
- Thermal oxidiser and incinerator components
- Nuclear reactor pressure vessel bolting
- Petrochemical reactor and regenerator bolting
- High-temperature valve bonnet bolting
Available Fastener Types
ASTM A453 Grade 660 Classes
A453 660 is available in four classes (A through D) with varying heat treatments and strength levels. Class A (solution treated + aged) and Class D (strain hardened + aged) provide the highest tensile strengths for critical high-temperature joints.
Creep & Stress Relaxation
Above 450°C, standard B7 bolts lose clamp load due to stress relaxation. B16, A453, and superalloy grades are specifically designed to maintain bolt load over 100,000+ hours of continuous high-temperature service.
Power Generation Expertise
EMG has extensive experience in supplying high-temperature bolting for coal, gas, biomass, and combined-cycle power plants. We understand BS 4882 Durehete specifications and can advise on material selection for UK and international power generation projects.
Standards & Documentation
All high temperature alloys fasteners are supplied with full documentation, EN 10204 3.1 mill test reports, and compliance with relevant industry standards.
EN 10204 3.1 Certification
Third-party verified material test reports with full chemical and mechanical data.
Heat Number Traceability
Complete material traceability from mill source through to final delivery.
PMI Testing
Positive Material Identification for critical alloy verification.
ISO 9001 Quality
Quality management ensuring consistent product quality and compliance.
Frequently Asked Questions
Common questions about high temperature alloys fasteners, specifications, and applications.
At what temperature should I switch from B7 to B16?
ASTM A193 B16 should be specified when sustained service temperatures exceed 450°C. Above this threshold, B7 bolts experience unacceptable stress relaxation and loss of clamp load. B16's chrome-moly-vanadium composition maintains bolt load over 100,000+ hours at temperatures up to 593°C.
What are the classes of ASTM A453 Grade 660?
A453 660 (A-286 superalloy) comes in four classes: Class A (solution treated + aged, 930 MPa), Class B (solution treated, 795 MPa), Class C (hot finished, 690 MPa), and Class D (strain hardened + aged, 860 MPa). Classes A and D provide the highest strengths for critical high-temperature joints.
What is creep and why does it matter for bolting?
Creep is the slow, time-dependent deformation of metal under sustained stress at elevated temperatures. In bolted joints, creep causes gradual loss of bolt tension (stress relaxation), leading to flange leaks. High-temperature alloys like A453 660 and Waspaloy are specifically designed to resist creep.
Can Waspaloy and Nimonic be used for bolts?
Yes. Waspaloy (Ni-Cr-Co-Mo) and Nimonic 80A/90 (Ni-Cr-Ti-Al) are precipitation-hardened nickel superalloys used for gas turbine and steam turbine bolting at temperatures up to 870°C. They maintain exceptional creep resistance and bolt load retention in continuous high-temperature service.
Need a Quote for High Temperature Alloys Bolting?
Tell us the grade, size and quantity you need in high temperature alloys — we'll confirm availability, certification level and lead time to your site.
Phone
+61 (0)7 4055 6928Emergency Support
24/7 availability for critical projects