Flange bolting is the most-substituted, least-understood component in piping — and the gasket can only do what the studs let it. Here's the grade system, the pairings, and the torque fundamentals that keep bolted joints tight.

The A193 Grade Family

Pair studs with the matching ASTM A194 nuts: 2H with B7 and B16, Grade 7 or 4 for L7 (impact-tested), 8/8M with the stainless grades. For sour (H2S) service, specify B7M/2HM with controlled hardness per NACE MR0175.

Coatings

Plain black studs suit painted, dry environments. Hot-dip galvanized and zinc add basic corrosion protection. For Gulf Coast plants, PTFE-based coatings (xylan-type, the familiar blue or green studs) have become the standard: they resist salt corrosion for years and — just as valuable — provide a consistent friction factor for torquing and let nuts break free at turnaround instead of being torched off.

Torque Fundamentals

Bolt torque targets come from the required gasket stress, not from a generic chart — the same B7 stud gets different torque with spiral wound vs sheet vs RTJ gaskets, and coated vs plain threads change the friction factor (K) significantly. The universal rules: lubricate threads and nut faces (unless the coating is the lubricant), tighten in a star/cross pattern, work up in at least three passes (30% – 60% – 100%), then do a final circular pass. On critical joints follow ASME PCC-1. Never mix used and new studs in one flange.

Length & Sizing

Stud length for standard ASME B16.5 flanges is tabulated by size and class — tell us the flange size, class, and gasket type and we'll confirm length rather than measuring corroded studs in the field.

Studs, Nuts & Gaskets — One Order

We stock B7 studs with 2H nuts, coated and plain, with MTRs available, alongside the gaskets they clamp. List size, length or flange spec, grade, coating, and quantity in the quote form at the top of the page — pricing back in 1–2 business hours.