Pipes & Fittings
Stud bolts, nuts, U-bolts and structural fasteners
CRS PLUS sources the bolting for flanged joints and pipe supports: fully threaded stud bolts with heavy hex nuts in ASTM A193 and A320 grades, U-bolts for pipe supports, hex bolts for structural connections and anchor bolts. Bolting is quoted by diameter, length, grade and coating, and can be supplied as complete sets per flange joint.
Bolting we quote
Sourced through the qualified supplier base. Sizes, ratings and grades are shown as ranges; send your bill of materials and every line is quoted against its exact specification.
| Product | Standard | Sizes | Grade | Finish |
|---|---|---|---|---|
| Stud bolt with 2 heavy hex nuts | ASTM A193 / A194, ASME B18.31.2 | ½ to 4 in (UNC / 8UN) | B7 / 2H | Plain, hot-dip galvanised, fluoropolymer coated |
| Stud bolt, sour service | ASTM A193 / A194, NACE MR0175 | ½ to 4 in | B7M / 2HM | Plain, hot-dip galvanised, fluoropolymer coated |
| Stud bolt, low temperature | ASTM A320 / A194 | ½ to 4 in | L7 / Gr 4 or 7 | Plain, coated |
| Stud bolt, stainless | ASTM A193 / A194 | ½ to 2½ in | B8 / B8M with 8 / 8M nuts | Plain |
| U-bolt with nuts (pipe support) | Manufacturer / MSS SP-58 type | Pipe NPS ½ to 24 | A193 B7, A36, stainless | Hot-dip galvanised, plain |
| Hex bolt and nut (structural) | ASTM A307, A325, ISO 4014 | M10 to M36; ½ to 1½ in | A307 Gr B, A325, 8.8, 10.9 | Black, hot-dip galvanised |
| Anchor bolt | ASTM F1554 | ½ to 2 in | Gr 36, 55, 105 | Black, hot-dip galvanised |
How flange bolting is specified
A stud bolt line gives the diameter and thread, the length, the stud and nut grades and the coating — for example "Stud + 2 nuts ⅝ in UNC × 90 mm, A193 B7 / A194 2H, hot-dip galvanised". The diameter and number of studs per joint follow from the flange size and class in ASME B16.5; the length depends on the flange type, facing and gasket thickness, so it is best taken from the project bolt table or the flange pairing.
For sour service, NACE MR0175 / ISO 15156 limits hardness, and the hardness-controlled grades B7M and 2HM are used. Low-temperature lines take A320 L7. Where bolts will be tightened by tensioning tools, studs are ordered with an extra diameter of thread length to suit.
Coatings
Hot-dip galvanising gives robust corrosion protection for outdoor plant and is the common choice for tank and structural bolting. Fluoropolymer coatings give a thinner, uniform layer and a lower friction coefficient, which helps controlled torqueing on process flanges. Nuts for galvanised studs are tapped oversize to accept the coating.
Documentation and supply terms
- Mill test certificate
- EN 10204 3.1 certificate for every line, traceable to the heat number marked on the item. EN 10204 3.2 with third-party witness on request.
- Marking
- Material grade, size, rating and heat number marked on each item to the governing standard (MSS SP-25 for valves, flanges and fittings).
- Inspection
- Positive material identification, dimensional checks and third-party inspection arranged where the project specifies them.
- Sour and low-temperature service
- NACE MR0175 / ISO 15156 hardness limits and impact testing applied where the piping class calls for them, and stated on the certificate.
- Quotation
- Each line states the standard, grade, origin, lead time and certification before you commit. Listing does not indicate stock held by CRS PLUS.
Frequently asked questions
What is the difference between B7 and B7M stud bolts?
Both are ASTM A193 chromium-molybdenum alloy steel. B7M is heat-treated to a lower maximum hardness and is 100% hardness tested, so it meets NACE MR0175 requirements for sour (H₂S) service. B7M has lower strength than B7, which is taken into account in joint design.
Which nut goes with a B7 stud?
The standard pairing is ASTM A194 grade 2H heavy hex nuts. For B7M studs in sour service the matching nut is 2HM.
How many stud bolts does a flange need?
It depends on size and class. A 4 in class 150 flange takes 8 studs of ⅝ in diameter; a 4 in class 600 flange takes 8 studs of ⅞ in. The full table is in ASME B16.5, and we can calculate quantities and lengths from a flange list.
What is a U-bolt used for?
A U-bolt holds a pipe to a support beam or saddle. It is specified by the pipe size it fits, the rod diameter, the thread and the material and finish, and is supplied with nuts and, where required, plates or washers.
Are bolts supplied with certificates?
Yes. Stud bolts and nuts are supplied with EN 10204 3.1 certificates showing chemistry, mechanical properties and, for B7M / 2HM, hardness test results. Coating thickness reports can be supplied for galvanised or coated bolting.
Request a bolting quotation
A structured offer follows within 72 hours.
Manufacturer and brand names, where mentioned, are used for identification only. CRS PLUS sources these products through its qualified supplier base and holds no distributor, reseller or agency appointment from any manufacturer.