Xylan-Coated B7 Stud Bolt 2H Heavy Hex Nut Fasteners in Challenging Environments

Xylan-coated ASTM A193 B7 stud bolts with A194 2H heavy hex nuts are the coated bolting set for flanged joints that see corrosion and need repeatable preload: the polymer coating lowers friction and keeps rust off the fasteners. The set works alongside our flange gaskets.

What the Coated B7 and 2H Set Is

ASTM A193 B7 studs are heat-treated chromium-molybdenum alloy steel, and A194 2H heavy hex nuts are their hardened partners — wider and thicker than standard hex to spread load on the flange. The Xylan coating is a PTFE-based polymer film applied over the fasteners: it seals the steel from moisture and gives a low-friction surface, so torque converts into preload instead of thread drag.

• ASTM A193 B7 stud — heat-treated Cr-Mo alloy steel for high strength.
• A194 2H heavy hex nut — wide bearing face, hardened to match the stud.
• Xylan coating — PTFE-based polymer film for corrosion and friction control.
• Coated threads — consistent torque-tension and easier breakout at teardown.

Corrosion Protection

Uncoated carbon steel bolting rusts fast in humid, coastal and chemical atmospheres, and the rust film wrecks torque consistency. The Xylan film acts as a barrier that does not depend on paint thickness the way galvanizing does, and it tolerates handling better than soft platings. Where the coating stays intact, fasteners survive exposure cycles and remain serviceable.

Key Benefits

• Barrier protection against humidity, salt spray and many chemicals.
• Low, stable friction — torque values repeat across joints and crews.
• Reduces galling and thread seizing on make-up and breakout.
• Extends service life of bolting in exposed environments.

Where They Are Used

Coated B7/2H bolting secures flanged joints on offshore platforms, pipeline stations, refineries, petrochemical units and power-plant utilities. It fits any joint that sees weather, washdown or mild chemical exposure and still needs reliable make-up.

In the Joint

The stud carries the preload through the flange while the gasket seals between the faces; keep the coating intact on washers and threads and torque evenly in a cross pattern. Pair the set with gaskets rated for the same media, and the pipe flanges must match the class the joint is designed for.

Installation and Care

Use the coating maker's torque values — dry-film friction changes the required torque versus bare steel. Torque in stages and cross-pattern, avoid sharp tools that cut the film, and touch up small damage at the washer face. At teardown, inspect threads and replace any stud with heavy coating loss; re-torque only per the joint's procedure.

Frequently Asked Questions

Why coat B7 bolting instead of using stainless?

B7 with Xylan gives alloy-steel strength at lower cost than stainless and adds corrosion and friction control; stainless is preferred when the media attacks carbon steel at the base metal level.

Does Xylan change the torque value?

Yes — the low-friction film needs lower torque for the same preload. Use the coated-bolting torque chart from the coating or gasket maker, not bare-steel values.

Can coated studs be reused?

Only if the coating is intact on threads and bearing faces; heavy wear, flaking or rust means the stud should be replaced.