ASTM Fastener Product Center
B7 B8 B8M
Professional manufacturer of high-strength and low-temperature fasteners for oil and gas,petrochemical,LNG,offshore,pressure vessel,and power plant projects.
ASTM A193 covers alloy steel and stainless steel bolting materials for high-temperature or high-pressure service. ASTM A320 covers alloy steel and stainless steel bolting materials for low-temperature service,including cryogenic and LNG-related applications.
Daiweike supports stud bolts,double-end studs,fully threaded rods,heavy hex nuts,coating selection,heat treatment,custom length production,marking,inspection,and export packaging.
Use strength,corrosion resistance,temperature condition,and nut pairing to choose the right ASTM bolting grade faster.
Best choice for alloy steel bolting in pressure,flange,valve,and high-temperature service.
304 stainless solution for cryogenic,LNG,low-temperature piping,and clean stainless assemblies.
316 stainless option for low-temperature service where chloride,offshore,or chemical corrosion matters.
Class 1 is normally supplied in a solution-treated condition for stainless grades. It is suitable when corrosion resistance and standard mechanical performance are the priority.
Class 2 receives additional strain hardening or treatment to achieve higher mechanical strength. It is selected where higher proof load or tensile performance is required.
Review practical purchase checkpoints for ASTM A193 / A320 stud bolts. Hover each item to see the related production reference.
Raw Material Control
Round bars,heat numbers,and material certificates form the basis of traceability.
Manufacturing Flow
Cutting,heat treatment,thread rolling,chamfering,inspection,packing,and shipment are managed as one traceable route.
Surface Finish Selection
The finish should match corrosion risk,friction requirement,thread fit,and installation environment.
Export Packing
Packaging should protect thread surfaces,preserve traceability,and fit the project delivery method.End-to-End / 端到端means the total length measured from the outermost end face to the opposite outermost end face.
Thread-to-Thread / 牙到牙means the distance between the first complete thread positions after the chamfers.
Fully Threaded Rodshould show continuous thread profile across the body,with chamfers at both ends.
Diameter,pitch,tolerance,and chamfermust match the drawing,nut,and flange assembly requirement.
These articles are written as practical purchasing and engineering references. Final grade,coating,and inspection requirements should always be checked against the latest project specification and applicable ASTM standard edition.
A193 is generally used for high-temperature or high-pressure bolting service,while A320 is used for low-temperature service. The practical difference is not just the name:grade,material condition,testing,and application temperature all affect selection.
B7 is an alloy steel strength-focused choice. B8 is 304 stainless for low-temperature stainless applications. B8M is 316 stainless when corrosion resistance is more important,especially offshore,chemical,or coastal environments.
Class designations relate to material condition and mechanical property requirements. Buyers should not treat CL1 and CL2 as interchangeable;the class must match the drawing,project specification,and required mechanical properties.
Confirm whether the drawing uses overall length,thread-to-thread length,thread length on each side,diameter,pitch,and chamfer requirement. Misunderstanding length definitions is a common cause of wrong production and site assembly issues.
Surface treatment should be selected by corrosion environment,installation friction,thread fit,storage condition,and project specification. PTFE and hot dip galvanizing both require attention to coating thickness and nut compatibility.
Yes,custom lengths are practical when drawings define diameter,thread pitch,length,chamfer,grade,class,finish,nut pairing,marking,and inspection documents. Custom production should start from clear technical data,not only a product name.
ASTM A194 nuts are commonly paired with ASTM bolting materials. Typical pairings include A194 2H with B7,A194 8 with B8,and A194 8M with B8M,but final selection should follow the project specification.
Common documents include material certificate,chemical analysis,mechanical test result,hardness,impact test when required,PMI for stainless,dimension report,thread gauge record,and heat-number traceability. Requirements vary by order and project.
ASTM A193 and ASTM A320 are both bolting material standards,but they are used in different service contexts. A193 is associated with alloy steel and stainless steel bolting materials for high-temperature or high-pressure service,such as flanges,valves,pressure vessels,and piping systems. A320 is associated with bolting materials for low-temperature service,including applications where impact performance and low-temperature suitability may matter. For purchasing,the important point is to specify the full grade and class,not just “A193” or “A320”. A buyer should also confirm nut pairing,coating,thread standard,marking,inspection documents,and the latest standard edition required by the project.
B7,B8,and B8M serve different engineering priorities. A193 B7 is an alloy steel bolting material selected when strength and pressure service are primary. A320 B8 is based on 304 stainless steel and is used when stainless low-temperature bolting is required. A320 B8M is based on 316 stainless steel and is normally considered when corrosion resistance is more demanding,such as chloride,offshore,chemical,or coastal environments. The final choice should consider temperature,corrosion,mechanical properties,magnetic property requirements,coating,nut pairing,and project documents.
Class requirements affect the material condition and mechanical property expectations of stainless bolting. In purchasing communication,CL1 and CL2 should be stated clearly because a supplier cannot safely infer the required class from the grade name alone. When a drawing or project specification states B8 CL2 or B8M CL2,the class requirement should be reflected in quotation,production route,inspection plan,and certificate review. If the class is missing from an inquiry,it is better to confirm it before production rather than assume.
Surface finish affects corrosion protection,handling,friction,thread fit,and installation. Plain finish is simple but needs controlled storage and timely installation. Black oxide provides appearance and light handling protection but should not be treated as heavy corrosion protection. PTFE coating is commonly used where corrosion resistance and controlled friction are important,but coating thickness and nut fit must be considered. Hot dip galvanizing provides zinc protection for outdoor service,but thread allowance and matching nut compatibility are important. Custom coatings should be reviewed against the real operating media,temperature,and assembly method.
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