Product Overview
A stud bolt is a small part with an outsized job: it's what holds a flanged joint together under pressure, and what lets you break that joint later without cutting anything loose. In refinery, petrochemical and power-plant piping, the default bolting grade for the job is ASTM A193 B7 - a chrome-molybdenum alloy steel stud, usually paired with an ASTM A194 2H nut.
We supply B7 stud bolts from 1/2" to 4" in plain, hot-dip galvanized, PTFE and Xylan finishes, in UNC and 8UN threads, fully threaded or as double-end studs with matching 2H nuts. If you're bolting up flanged joints in high-temperature or high-pressure service, this is the grade your piping spec most likely calls out.
Kennen Steel International Co., Ltd. is a China-based steel trading company and a first-tier mill agent. We don't run a factory - we buy direct from vetted source mills, hold them to the specification you agree, and manage the export side end to end. Three decades of steel trading in China and a vetted network of source mills is what stands behind every order.
Most of our stud bolt shipments go to MRO distributors, valve and flange traders, and plant contractors across Africa, the Middle East and Southeast Asia - buyers who need the right grade, a matched nut, honest packing and paperwork that clears the gate.
Key Advantages
Direct mill supply, not a resold catalogue
We buy from the mills and we inspect what they make. The grade stamped on the stud is the grade in the box, and if a batch doesn't meet the agreed specification it doesn't ship. You get mill quality with someone accountable for the order.
B7 and 2H supplied as a matched set
Studs and nuts are a system, not two separate purchases. We supply B7 studs with matching ASTM A194 2H nuts - and 2HM where a sour-service or lower-hardness nut is called for - so the joint is correct from the start and you're not chasing hardware after the studs arrive.
Chrome-moly for hot, high-pressure duty
B7's chrome-molybdenum chemistry is what makes it the standard choice for flanged joints that see elevated temperature and pressure. Tensile and yield follow ASTM A193 B7, with the actual figures for the heat stated on the mill test certificate.
Threads that match your piping spec
UNC as the everyday series; 8UN where the larger imperial sizes call for it. Send us the line spec and we'll supply the thread series and stud form it assumes - fully threaded or double-end.
Coatings for the environment it lands in
Plain (black) for the usual high-temperature service, hot-dip galvanized for outdoor and atmospheric exposure, and PTFE or Xylan coatings where controlled friction and easier break-out are wanted. Coating choice is a spec decision - tell us the service and we'll confirm what fits.
B7M available for sour service
Where the line is wet H2S, B7M to NACE MR0175 may be the specified grade rather than plain B7. We can quote it as a related variant - availability and documentation are confirmed per order.
Documents that clear the gate
An EN 10204 3.1 mill test certificate per batch comes as standard, dimensional inspection is run to the cited standard, third-party inspection can be arranged on request, and we support the destination conformity paperwork some markets require, such as KEBS or PVoC.
Technical Specifications
| Item | Specification |
|---|---|
| Product Name | B7 Stud Bolts (chrome-moly alloy steel stud bolts with A194 2H nuts) |
| Standard | ASTM A193 B7 (stud bolts); matching nuts to ASTM A194 2H / 2HM |
| Material | AISI 4140 / 4142 chrome-molybdenum alloy steel |
| Grade | B7 (B7M to NACE MR0175 available as a related variant, to be confirmed) |
| Size Range | 1/2"–4" (M12–M100) |
| Length | Made to order |
| Stud Form | Fully threaded, or double-end / stud with hex nuts at each end |
| Thread Series | UNC as standard; 8UN for larger imperial sizes as specified |
| Mechanical Properties | Per ASTM A193 B7 - nominal values are approximately 860 MPa tensile and 725 MPa yield (class 2B); actual figures confirmed per heat on the mill test certificate |
| Hardness | Per ASTM A193 B7 - the specified limit is confirmed per batch on the mill test certificate |
| Service Temperature | Suitability confirmed against ASTM A193 B7 and your joint design; the recommended limit is confirmed per application |
| Finishes / Coatings | Plain (black), hot-dip galvanized (HDG), PTFE, Xylan |
| Coating Thickness | Confirmed per order |
| Matching Nuts | ASTM A194 2H (2HM on request) |
| Marking | Grade and heat / lot marking per the cited standard; confirmed per order |
| Dimensional Tolerance | In accordance with the cited standard; confirmed per size |
| Packing | Wooden cases or drums with protective lining, strapped for export |
| Certificate | EN 10204 3.1 mill test certificate per batch |
Grade, thread series, form, coating and packing are confirmed against your piping specification and destination before the order is placed.
Step-by-Step Manufacturing Process
- Bar selection - chrome-moly round bar of the required grade is inspected and cut to length. The chemistry chosen here is what makes the stud a B7 rather than a general-purpose bolt.
- Heating and forming - the bar is heated and shaped to the stud profile, with ends chamfered so the nut starts cleanly.
- Heat treatment - quenching and tempering develop the mechanical properties called for by ASTM A193 B7, tuning the balance between strength and toughness.
- Thread rolling - threads are rolled rather than cut, which keeps the grain flow continuous through the thread and gives a stronger thread than a cut one.
- Thread gauging - threads are gauged against the specified series (UNC or 8UN) so the stud and the nut actually mate.
- Coating - plain, hot-dip galvanized, PTFE or Xylan coating is applied where specified; the coating step and any pre-treatment are confirmed per order.
- Testing and marking - mechanical and hardness tests are run on samples from the batch, the stud is marked with grade and lot, and the batch certificate is raised.
- Packing - studs and matching nuts are packed with protective lining into wooden cases or drums, strapped for export.
Quality Assurance & Certificates
- EN 10204 3.1 mill test certificate per batch - chemistry, mechanical properties and hardness
- Dimensional inspection against the cited standard (ASTM A193 B7 / A194 2H)
- Thread gauging per size and series (UNC / 8UN)
- Coating thickness check for HDG, PTFE and Xylan finishes
- Third-party inspection available on request (SGS, BV, Intertek)
- Documentation support for destination conformity schemes (for example KEBS or PVoC)
- Every shipment is checked against the agreed specification before it leaves, so what lands matches what was ordered
Core Applications
- Flanged joints in refinery and petrochemical piping
- Power-station piping, steam lines and turbine connections
- Heat exchangers, pressure vessels and reactors
- Valve, pump and flange assemblies
- Oil, gas and process pipelines in high-temperature and high-pressure service
- MRO distributor stock and plant maintenance programmes
- B7M for sour-service (wet H2S) duty, where specified
FAQ
What is a B7 stud bolt used for?
It's the bolting for flanged joints in high-temperature and high-pressure service - refineries, petrochemical plants, power stations and heat exchangers. ASTM A193 B7 is the grade most piping specs call out for those joints, normally paired with an ASTM A194 2H nut.
What's the difference between B7 and B7M?
B7 is the standard chrome-moly grade. B7M is the variant intended for sour service and is specified to NACE MR0175, with a lower hardness limit and tighter hardness control. If the line handles wet H2S, your spec will usually say B7M. We can supply it as a related variant - tell us the service and we'll confirm availability and documentation.
Should I use UNC or 8UN thread?
UNC is the everyday imperial series; 8UN is common on larger sizes and where the piping spec calls for it. It's a spec decision, not a preference - send us the line specification and we'll supply the series it assumes.
Do the studs come with nuts?
Yes. B7 studs ship with matching ASTM A194 2H nuts, and 2HM where a sour-service or lower-hardness nut is required, so the joint is correct from the start.
Which coating should I choose?
Plain (black) for the usual high-temperature service, hot-dip galvanized for outdoor and atmospheric exposure, PTFE or Xylan where controlled friction and easier break-out are wanted. Coating choice depends on the service environment - tell us where the joint is going and we'll confirm what fits.
What are the mechanical properties?
B7 follows ASTM A193 B7, with nominal values around 860 MPa tensile and 725 MPa yield for class 2B. The actual figures for your heat are stated on the mill test certificate - we quote the certificate, not a brochure number.
Do you provide test certificates and inspection?
Yes. Every batch ships with an EN 10204 3.1 mill test certificate covering the agreed details. Third-party inspection (SGS, BV, Intertek) can be arranged on request, and we can support destination conformity documentation such as KEBS or PVoC where your market requires it.
Can you supply non-standard lengths or a specific thread form?
Yes - stud lengths are made to order. Send us the size, thread series and stud form (fully threaded or double-end) from your piping spec and we'll confirm before you commit.
Are you the manufacturer?
No. We're a China-based steel trading company and a first-tier mill agent. We buy direct from vetted source mills, verify grade and dimensions, and manage the export - coatings, packing, certificates and shipping. You get mill quality with someone accountable for the order.
