ASTM A193 and A320 stud bolts and heavy hex nuts

Stud Bolt Supply

Stud bolts selected by service condition, grade and joint requirements.

A procurement guide for continuous-thread and double-end studs used in flange joints, pressure equipment and low-temperature service. Compare A193 and A320, then confirm grade, class, dimensions, matched nuts, finish, tests and traceability.

Send RFQ by WhatsApp Study A193 Study A320 Standard Albums

A193 B7 / B8 / B8MA320 L7 / B8 / B8MContinuous / Double-endGrade + ClassMatched Nuts + FinishMTC + Impact Evidence

A193 and A320 define different service scopes, not two interchangeable product names.

Both can include alloy-steel and austenitic stainless grades. The deciding information is the governing standard and edition, design conditions, grade and class, mechanical and temperature requirements, dimensions, matched nuts and ordered evidence.

ASTM A193

Scope: Alloy-steel and stainless-steel bolting for pressure vessels, valves, flanges and fittings in elevated-temperature, high-pressure or other special-purpose applications.
Common grades: B7, B7M, B8, B8M and other alloy or stainless grades according to project requirements.
Material logic: B7 is an alloy-steel route; B8 and B8M are austenitic stainless routes. Grade, class or condition must be written with the standard.
Buyer check: Confirm standard edition, grade/class, thread, length basis, matching nut, finish, supplementary requirements and MTC traceability.

ASTM A320

Scope: Alloy-steel and stainless-steel bolting for pressure vessels, valves, flanges and fittings in low-temperature service.
Common grades: L7, L7M, B8, B8M and other project-selected low-temperature bolting grades.
Material logic: L7 is an alloy-steel route; B8 and B8M are austenitic stainless routes. Grade and class must be tied to the A320 order.
Buyer check: Confirm design temperature, impact-test condition and reports, grade/class, matched nut, dimensions, finish and traceability.

Ordering rule: never send only “B7”, “L7” or “stainless stud bolt”. State the standard and edition, grade and class, design temperature, diameter and thread, overall or effective length, end configuration, matched nuts, finish, quantity, marking, packing and required documents.

Open a dedicated standard album for deeper study.

Choose A193 or A320 to review the grade logic, matching nuts, surface treatment, inspection documents and RFQ checkpoints in a focused page.

Standard Album

ASTM A193

Bolting for elevated-temperature, high-pressure or other special-purpose applications. Study B7/B7M, B8/B8M, grade/class, matched nuts, finish and traceability.

B7 / B7MB8 / B8MA194 2HPTFE / HDG

Study A193

Standard Album

ASTM A320

Low-temperature bolting. Study L7/L7M, B8/B8M, impact requirements, matching nuts, stainless grades and packing marks.

L7 / L7MB8 / B8MA194 7MLow temperature

Study A320

B7, L7, B8 and B8M: four grade routes buyers should not mix.

Use the grade name only as a starting point. Material family, governing standard, class or condition and service requirements must remain together.

B7

Quenched-and-tempered chromium-molybdenum alloy-steel bolting under A193.

Pressure, elevated-temperature or special-purpose scope.
Confirm grade/class, dimensions, nut and finish.
Link MTC heat number to product and packing.

L7

Alloy-steel bolting under A320 for low-temperature service.

Do not substitute by chemistry similarity alone.
State design temperature and impact condition.
Confirm matched nut and impact-test evidence.

B8

Austenitic stainless bolting based on the Type 304 material family.

May be ordered under A193 or A320 as applicable.
State the governing standard and class/condition.
Review galling, lubrication and joint compatibility.

B8M

Molybdenum-bearing austenitic stainless bolting based on the Type 316 family.

Selected for corrosion compatibility, not as “stronger B8”.
State the governing standard and class/condition.
Confirm environment, mating material and finish.

Materials, process, surface treatment and packing are shown as a hover-based inspection flow.

Move over each step to see the corresponding production or packing scene. This is designed for buyers checking real procurement details, not decoration.

Raw materialCheck material grade, heat number, diameter and certificate before release.

Cutting and blankingCut bars to rough length, leaving allowance for thread and end preparation.

Heat treatmentApply required heat treatment according to grade, then verify mechanical performance.

Thread rollingRoll or form threads according to drawing and thread standard, then inspect fit.

Surface treatmentSelect plain, black oxide, PTFE, hot dip galvanized or project coating by service environment.

Export packingProtect threads, keep labels visible and connect each batch with documents.

Procurement control pointRaw material must be traceable before production release.

Overall length and effective full-thread length must be marked clearly.

The diagram uses a fully threaded stud with flat end faces and small chamfers. The lower dimension is the usable full-thread length, not thread pitch or tooth spacing.

All-thread stud catalog drawing: flat end faces, edge chamfers, overall length and effective full-thread span

End-to-end length is the overall length from one flat end face to the other flat end face, including chamfered end areas.

Effective full-thread length is the usable threaded portion between the first complete thread zones. It is not thread pitch, tooth spacing or the distance between two individual thread peaks.

For RFQ, confirm whether the drawing calls out overall length, effective thread length, chamfer, end style and thread standard.

Surface treatment and packing must match the installation environment.

For ASTM bolting, coating is not only appearance. It can affect corrosion resistance, nut fit, torque behavior, storage and final site acceptance.

Surface treatment

Plain, black oxide, hot dip galvanized, PTFE and project coatings should be confirmed with corrosion risk, friction requirement and thread fit.

Inspection documents

Confirm MTC, heat number, dimensions, thread gauge, hardness, mechanical test and PMI when stainless identification is required.

Export packing

Protect threads from damage and rust. Labels should connect standard, grade, size, heat number, batch and purchase order.

Plastic bags for small lotsCartons before outer packingPlywood boxes for exportPalletized loading for site receiving

Send your ASTM bolting list with grade, diameter, length basis, surface and quantity.

We will check the standard, matching nuts, surface treatment, packing marks and required documents before quotation.

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