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    ASTM A193 Grade B7 Stud Bolt Kits

    Quenched and tempered chromium-molybdenum stud bolts supplied as complete kits with ASTM A194 Grade 2H heavy hex nuts and full EN 10204 3.1 certification.

    Hot-dip galvanised ASTM A193 B7 stud bolts with ASTM A194 2H heavy hex nuts
    Hot-dip galvanised A193 B7 studs supplied as kits with A194 2H heavy hex nuts
    EN 10204 3.1 Certified
    ISO 9001 Quality
    Boxed hot-dip galvanised ASTM A193 B7 stud bolt kits ready for project dispatch
    HDG B7/2H kits boxed and matched by heat number before dispatch

    Overview

    ASTM A193 Grade B7 is the default stud bolt material for high-pressure, elevated-temperature flanged joints across oil and gas, LNG, refining and power generation. It is a quenched and tempered AISI 4140 chromium-molybdenum alloy steel with a minimum tensile strength of 862 MPa (125 ksi) and minimum yield of 724 MPa (105 ksi) in diameters up to 2-1/2in, and is almost always paired with ASTM A194 Grade 2H heavy hex nuts so that nut proof load exceeds stud strength. EMG supplies B7 studs from 1/4in to 6in diameter and M5 to M150 in continuous thread and double-end configurations, cut to any length, with Xylan 1424, GEOMET, PTFE, hot-dip galvanising or plain black finishes.

    ASTM A193 B7 stud bolts from EMG are supplied as complete kits — stud, two A194 2H heavy hex nuts and optional hardened washers — matched by heat number and covered by a single EN 10204 3.1 mill certificate.

    Typical Applications

    • ASME B16.5 and B16.47 raised-face flange bolting on process piping
    • Pressure vessel manways, blind flanges and closure bolting
    • Heat exchanger shell and channel flange assemblies
    • Valve body-to-bonnet and actuator mounting connections
    • Compressor and pump casing joints on hydrocarbon duty
    • Refinery and LNG shutdown and turnaround replacement bolting

    B7 Configurations We Supply

    • Continuous (all-thread) B7 stud bolts cut to project length
    • Double-end B7 studs with defined grip and threaded ends
    • Tap-end B7 studs for blind tapped holes
    • Complete B7/2H kits with two heavy hex nuts per stud
    • B7/2H kits with ASTM F436 hardened washers added
    • Coated B7 kits in Xylan 1424, GEOMET 321/500 or hot-dip galvanised

    Common Materials & Grades

    ASTM A193 B7AISI 4140 / 42CrMo4ASTM A194 2H nutsASTM F436 washersASTM A193 B7M (sour service)ASTM A320 L7 (low temperature)

    Standards & Documentation

    • ASTM A193/A193M for alloy and stainless steel bolting for high temperature service
    • ASTM A194/A194M Grade 2H for the mating heavy hex nuts
    • EN 10204 3.1 mill test reports covering chemistry, mechanical properties and heat treatment
    • Heat number traceability from billet through machining, heat treatment and coating
    • Thread inspection to ASME B1.1 Class 2A or ISO 261/965 as specified
    • Hardness verification and PMI available as an additional test package

    NEED MACHINED COMPONENTS TOO?

    Spacers, blinds, special nuts, shafts and bushes — supplied to your drawing with the same traceability as your bolting. Precision Machined Components →

    RELATED RESOURCES

    Stud Bolts HubConfigure a Stud Bolt KitB7M Sour Service StudsMetric B7 Stud BoltsNuts & WashersFastener CoatingsASTM StandardsAPI BoltingAlloy Steel Materials

    Mechanical properties and diameter effects

    B7 is supplied quenched and tempered with a minimum tempering temperature of 593 C. Up to and including 2-1/2in diameter the grade delivers 862 MPa minimum tensile and 724 MPa minimum yield with 16 percent elongation and 50 percent reduction of area. From over 2-1/2in to 4in the requirement steps down to 793 MPa tensile and 655 MPa yield, and above 4in to 724 MPa tensile and 517 MPa yield. Specifying engineers sizing large-diameter closure bolting need to work from the correct band rather than the headline 125 ksi figure, and EMG certificates state the actual tested values for the heat supplied so the calculation can be checked against real data.

    Why B7 is paired with A194 2H nuts

    ASTM A194 Grade 2H is a medium-carbon steel nut, quenched and tempered, with hardness and proof load selected so that the nut thread strips only after the stud has yielded. That is the behaviour a flange designer wants, because a stud failure is detectable while a stripped nut thread can hold pressure and then release without warning. Substituting a lower grade nut, mixing metric nuts onto imperial studs, or reusing nuts of unknown history all defeat that design intent, which is why EMG ships kits rather than loose components and certifies the stud and nut heats together.

    Service limits, coatings and friction

    Plain B7 has no corrosion protection and will scale in outdoor and marine service, so most Australian projects specify a coating. Xylan 1424 gives a low, repeatable coefficient of friction that suits torque-controlled tightening and resists disassembly seizure. GEOMET 321 and 500 give sacrificial zinc-flake protection without hydrogen embrittlement risk. Hot-dip galvanising to AS/NZS 4680 is common on structural and onshore utility bolting but adds thread clearance requirements and changes torque behaviour. Because friction drives how much of an applied torque becomes bolt load, the coating must be nominated before torque tables are issued — EMG supplies coating type and batch details on the certification pack so the joint procedure matches what was installed.

    When B7 is the wrong choice

    B7 should not be used where H2S is present in the process stream; NACE MR0175 / ISO 15156 sour service calls for hardness-controlled ASTM A193 B7M. For design temperatures below minus 29 C the low-temperature impact-tested equivalent ASTM A320 L7 or L7M applies. Above roughly 500 C sustained service, ASTM A193 B16 is the usual step up. Where the joint is exposed to seawater or the flange itself is a corrosion-resistant alloy, stainless B8M or a nickel alloy or duplex stud avoids galvanic and pitting problems. EMG stocks and supplies every one of those alternatives, so the grade can be selected on engineering grounds rather than availability.

    FREQUENTLY ASKED QUESTIONS

    Technical FAQs

    What nuts are supplied with ASTM A193 B7 stud bolts?

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    ASTM A194 Grade 2H heavy hex nuts. Two nuts per stud are standard, and we match the nut heat to the stud heat so a single EN 10204 3.1 certificate covers the complete kit. ASTM F436 hardened washers can be added where the flange face or spotface requires them.

    What sizes and lengths of B7 stud bolts can EMG supply?

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    1/4in through 6in diameter and M5 through M150, in any length. Standard ASME B16.5 flange lengths are available from stock or short-cycle manufacture, and non-standard lengths are cut, threaded and re-certified to order. Diameters above 6in are quoted on a project basis.

    Can B7 stud bolts be used in sour service?

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    No. B7 hardness is not controlled to the limits NACE MR0175 / ISO 15156 requires for wet H2S environments. Specify ASTM A193 B7M instead, which is tempered to a maximum 235 HBW and hardness tested on every stud.

    What is the temperature range for A193 B7 bolting?

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    B7 is a high-temperature grade suitable for continuous service to roughly 400 to 500 C depending on the applicable code and the joint design, with a lower limit of minus 29 C because it is not impact tested. Below that, use ASTM A320 L7 or L7M; for sustained higher temperatures, use ASTM A193 B16.

    Do you supply B7 studs coated to a specific customer specification?

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    Yes. Coating systems are applied strictly to the customer specification — we do not substitute. Nominate the system (for example Xylan 1424, GEOMET 321, GEOMET 500, PTFE or hot-dip galvanising to AS/NZS 4680) and the applicator certificate is included in the documentation pack.

    What lead time applies to B7 stud bolt kits in Australia?

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    Common sizes in standard flange lengths ship from Australian stock within days. Non-standard lengths, coated kits and large diameters typically run three to six weeks depending on coating and testing scope. Shutdown and breakdown requirements are handled through RapidBolt, our 24/7 emergency bolting service.
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