Quenched-and-tempered alloy-steel bolting widely used for pressure and elevated-temperature applications. Confirm diameter-dependent requirements, threads, finish, matched nuts and inspection documents.
ASTM A193 / A193M-26
High-temperature, high-pressure and special-purpose bolting.
ASTM A193/A193M covers alloy-steel and stainless-steel bolting for pressure vessels, valves, flanges and fittings. Yes, the standard includes B8 and B8M as well as alloy-steel grades such as B7. Grade, class or condition and the governing project requirements must be stated together.
B7 · Cr-Mo alloy steelB8 · Type 304 stainless familyB8M · Type 316 stainless family
Do not select by grade name alone.
A193 identifies the bolting specification and service scope. The grade identifies the material route; B8/B8M class or condition affects processing and mechanical requirements. Final selection remains a design and purchase-order decision.
Stainless bolting under A193. State the required class or condition; solution-treated and strain-hardened products are not interchangeable descriptions.
Molybdenum-bearing stainless route selected for corrosion compatibility. B8M is not simply a higher-strength B8; service environment and ordered class still govern.
Product forms
Real product-reference photography is used to show form and finish. Marking and appearance alone do not prove the ASTM grade; MTC, heat traceability and ordered tests remain required evidence.
Continuous-thread stud / all-threadThreaded over the complete length. Specify overall end-to-end length, thread series, chamfer and nut quantity.
Double-end / tap-end formSmooth body with threaded ends; tap-end or single-end geometry must be confirmed by drawing, thread lengths and installation method.
Surface treatment options
Coating is an ordered requirement, not part of the grade name. Availability and suitability depend on material, service, thread fit, coating process and project approval.
Plain / black
Common alloy-steel supply appearance; preservation and service corrosion requirements must be confirmed.
PTFE-type coating
Specify approved coating system, color, thickness, lubrication/friction requirement and nut fit.
Hot-dip galvanized
Use only when the project permits it; confirm coating thickness, oversize nut/thread allowance and assembly compatibility.
Stainless plain / passivated
For B8/B8M family products, state surface condition, cleaning/passivation and anti-galling requirements where applicable.
Images illustrate product form and finish only. Final grade, class, chemistry, mechanical properties and traceability are controlled by the order and inspection documents.
RFQ data that prevents errors
For flange or pressure-equipment procurement, send the complete designation instead of only “B7” or “B8M”.
Standard + editionASTM A193/A193M and project specification.
Grade + classB7, B8, B8M and class/condition where applicable.
Thread + fitMetric/UNC/8UN, pitch or TPI, tolerance and nut fit.
Length basisEnd-to-end, effective thread length and end style.
Matched componentsNut grade, quantity and washer requirement as ordered.
Finish systemCoating standard, thickness, color and lubricant.
EvidenceMTC, heat number, tests, PMI or inspection plan.
Commercial dataQuantity, packing, marks, destination and schedule.