Hot-Shot B7 Stud Bolts & 2H Nuts — Houston, 24/7
A193 B7 stud bolts with A194 2H heavy hex nuts are the bolting on most refinery, chemical-plant and power-station flanges, and the bolting most often needed in a hurry. We cut them from certified bar in Houston, thread, chamfer and mark them, run on the nuts and ship. Call 832-446-3442, answered 24/7; Gulf Coast plants get them on our own hot-shot.
Standard studs, bolts and nuts in stocked grades can ship the same day; machined parts to a drawing are typically a few days depending on material and heat treatment. A typical rush such as 50 sets of 7/8 in. × 6 in. B7 studs with 2H nuts, cut from bar on the shelf, can ship the same day. B7 bar is quenched and tempered before it is threaded, so plain B7 studs never go to the heat treater. B7M does: ASTM A193 calls for a final stress relief after machining.
What we make, and what happens after machining.
| Grade | UNS | After machining | Chosen for |
|---|---|---|---|
| A193 B7 | G41400 · G41420 · G41450 | Nothing — Q&T bar | The standard alloy-steel stud: 4140-type steel, quenched and tempered, 125 ksi tensile up to 2½ in. |
| A194 2H | — | Q&T nut | The usual heavy hex nut for B7, proof loaded at 175 ksi. |
| A193 B7M | G41400 · G41420 · G41450 | Stress relief, outside | B7 held to 22 HRC max for NACE MR0175 sour service; hardness tested on every piece. |
| A194 2HM | — | Q&T nut, 235 HBW max | The sour-service nut for B7M and L7M studs. |
| A194 7 | G41400 · G41420 · G41450 | Q&T nut | The Cr-Mo nut used with B7 at temperature, and required on L7. |
Where these parts go.
- ASME B16.5 and B16.47 flanges on refinery, chemical and power-plant piping.
- Valve bonnet and body bolting.
- Pump and compressor casings.
- Heat exchanger channel covers and shell flanges.
- Pressure-vessel manways and nozzles.
- Sour gas, amine and hydrotreating units, in B7M with 2HM nuts.
So we can start on the call.
- Diameter, thread and length. Studs are UNC up to 1 in. and 8 UN above unless you say otherwise, and length is measured first thread to first thread.
- The quantity, and the nuts: two heavy hex nuts per stud unless you say otherwise.
- For sets, the flange list — NPS, pressure class and how many flanges — and we count the studs from ASME B16.5 or B16.47.
- Sour service? Say B7M and 2HM, or NACE MR0175, at the start.
- Any coating. PTFE, zinc-flake or galvanizing is applied outside and adds time.
Plain B7 is the fastest bolting there is to make.
- Plain B7 with 2H nuts, uncoated, with the standard 3.1 report: sawn, threaded, chamfered, marked and shipped.
- B7M and 2HM add the post-machining stress relief by an outside heat treater and a hardness test on every piece to the 22 HRC limit.
- Coatings go to an approved Houston processor. Hot-dip galvanized nuts are tapped oversize after coating so they fit (ASTM A563).
- B7 and B7M studs, or 2H and 2HM nuts, look the same and are told apart only by their marking; ask for PMI or keep the grades in separate sets if both are on site.
Heat treatment and coating are done by approved Houston processors, outside our shop. Every lot ships with an EN 10204 3.1 report; certification & traceability.
Order them at the start.
Hardness testing
A Rockwell or Brinell indenter is pressed into the part and the indentation measured. Hardness tracks the heat treatment, so it catches an under-tempered lot, and sour-service grades carry a hardness ceiling that every piece must meet.
Does it meet the strength table?Tensile testing
The full-size fastener is pulled to failure to prove the load it carries, and a specimen machined from the lot gives tensile strength, 0.2 percent offset yield, elongation and reduction of area. All are compared with the grade's table by diameter.
Will the nut carry the bolt's full load?Proof load testing of nuts
The nut is threaded on a hardened mandrel and loaded to the proof stress for its grade and size. It passes if the threads neither strip nor break and it can be removed by hand afterwards; a wrench may start it, for up to half a turn.
Does every dimension and thread meet the drawing?Thread gauging and dimensional inspection
Threads are checked with Go and No-Go ring and plug gauges, and pitch diameter is measured by the three-wire method or on a thread comparator. Heads, flats, lengths and radii are measured with calibrated instruments and, for complex parts, on the CMM.
Is the alloy what the paperwork says?Positive Material Identification (PMI)
A handheld X-ray fluorescence analyser reads the chemistry of the finished part in seconds and matches it to the grade. It confirms that a B7 is chromium-molybdenum steel and not plain carbon, that a B8M has its molybdenum, and that a nickel-alloy stud is the alloy on the certificate. Handheld XRF does not read carbon, so carbon is confirmed from the mill certificate or by spark (OES) analysis.
Jobs we’ve made in these grades.
Common questions.
Can I get B7 stud bolts at night or on a weekend?
Yes. Call 832-446-3442; the line is answered 24/7 and our hot-shot runs around the clock across the Gulf Coast. We give you a delivery time on the call.
Which nut goes with a B7 stud?
B7 studs usually take A194 2H heavy hex nuts. For sour service the M grades go together: B7M studs with 2HM nuts. L7 studs must take Grade 7 nuts (ASTM A320).
Is B7M the same as B7?
It is the same steel, tempered to 22 HRC maximum for NACE MR0175 sour service, stress relieved after machining and hardness tested on every piece. Do not use B7 where B7M is specified.
How is stud bolt length measured?
From first thread to first thread, not counting the chamfered points; each point is one to two threads long (ASTM A193, A962).
Can you coat B7 studs on a rush order?
Yes — PTFE, zinc-flake, hot-dip galvanizing and other finishes are applied by approved Houston processors. Coating adds a step to an emergency order, so tell us at the start whether it is required.