M12 x 1.75 Bolt Kit for 6" Heavy Duty High Pressure Tri Clamp, Deep Brass Nut

Replacement hardware for the heavy casting 6 inch high pressure tri clamp. One set is one bolt, one split lock washer, one deep brass nut. A clamp takes two sets.

The nut and washer are sold on their own because they are the parts that wear out.

Check this is your hardware first

Put a wrench on the nut.

• 3/4 inch wrench and an M12 bolt: this is your hardware
• 5/8 inch wrench and a 3/8 inch bolt: you need the 3/8 inch set instead

The thread is M12 x 1.75, metric. These clamps get called half inch bolt clamps and the hardware gets listed as 1/2 inch, but M12 measures 0.472 inches and a 1/2"-13 bolt measures 0.500 inches. A hardware store bolt will not thread into this nut.

It does not fit a standard 6 inch tri clamp, and it does not fit any clamp closing on 3/8 inch hardware.

Specifications

Torque is set by the gasket, not by the clamp. Which gasket you run decides whether you pull 30 or 50 in-lbs, and that choice is covered in Choosing the Right Gasket Material for Tri-Clamp Connections.

Why brass, and why so tall

Stainless threaded into stainless galls and seizes, and the nut ends up cut off. Brass on a stainless bolt does not gall, so the joint can be broken and remade over and over. We do not offer a stainless nut for this clamp.

The nut stands 1.7 times the height of a standard M12 nut, so it engages 1.7 times the thread. That engagement is what holds a 6 inch joint at pressure through repeated cycles.

Replace on a schedule, not on appearance

• Brass nut: every 6 months in service
• Bolt: every 12 months
• Any nut that runs on noticeably easier or harder than the one beside it

The brass nut is the softest part in the joint by design, so it deforms instead of the bolt. After several cycles the torque needed to reach the same clamp load climbs, and the wrench stops telling you what is actually holding the joint. There is no published cycle count for this nut, and anyone who gives you one is guessing.

The split lock washer is not optional. A flattened, reused washer is the most common reason a heavy clamp loosens between services.

Stock and lead time

Complete sets and brass nuts ship from Bend, Oregon. Split lock washers are restocked within a week. Worst case lead time on any part of this kit is 30 days.