Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Durehete in Refinery and Petrochem Fired-Heater Bolting — Durehete 1055 + 950 in convection and radiant sections
Refinery and petrochem fired heaters carry process fluid through tube bundles in radiant and convection sections. The bolting selection covers tube-support hangers, tube-sheet flange bolts and burner-mount studs. Durehete 1055 covers the radiant section at 540°C+; Durehete 950 covers the convection section.
Radiant-Section Bolting
Radiant-section tube hangers and casing flange bolts see metal temperatures of 540-590°C. Durehete 1055 / Alloy T41 covers the upper end; the Ti+B microalloying handles the long-duration thermal-cycle exposure between scheduled outages.
Convection-Section Bolting
Convection-section casing flange bolts run cooler, typically 400-480°C. Durehete 950 / Alloy T31 covers the band; ASTM A193 B16 dual certification is common because US-spec refineries source against ASTM bolting standards.
Burner-Mount Bolting
Burner-mount studs see direct flame proximity. Durehete 1055 is specified at the upper temperature; oxidation resistance becomes the limiting factor above 565°C and warrants escalation to a stainless or nickel-base grade.
Turnaround Re-Tightening
Refinery turnaround cycles typically 4-5 years. Bolt re-tightening is scheduled at each turnaround stress-relaxation data. Replacement of bolting occurs when residual preload drops below the gasket leak threshold or when visual inspection finds creep cracking.
Frequently Asked Questions
Which Durehete grade is specified for refinery and petrochem fired-heater bolting?
The grade depends on service temperature. Durehete 1055 (T41 / 1.7729) covers up to 565 degrees Celsius; Durehete 950 (T31 / 1.7711) covers up to 540 degrees Celsius; Durehete 900 (T22 / 42CrMoV5-6) covers up to 500 degrees Celsius.
What standard governs refinery and petrochem fired-heater bolting?
EN 10269 is the controlling European bolting-steel standard. ASTM A193 Grade B16 is the closest US equivalent for the lower-temperature grades (Durehete 950 and 900).
Are dual certificates available?
Yes. TorqBolt supplies the Durehete grades with EN 10269 type 3.1 / 3.2 inspection certificates plus ASTM A193 dual certification when the procurement specification requires it.
What is the typical lead time?
Lead time depends on size and quantity. Stock sizes ship within a week; custom-machined fasteners run 4-8 weeks from heat traceability through to delivery.
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