SS 321 Slip On Flange

QS Flange: Putian Ss 321 So Flange

Slip on flange in titanium stabilized 321 stainless steel, welded over the pipe end for lines that see heat, exhaust gas and repeated thermal cycling.

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One-Minute Overview

Slip on flange in 321 stainless, slid over the pipe end and fillet welded on both sides.
Titanium stabilization keeps the welded zone from losing corrosion resistance after heat.
Size, pressure class and facing stay open until your line data is confirmed on inquiry.
Common on exhaust, heat exchanger and steam traced runs that cycle in temperature.

A slip on flange is positioned by the pipe rather than by a butt weld, so the fitter sets the flange square on the pipe end, tacks it, then runs two fillet welds, one at the hub and one inside the bore. The hub weld carries the axial thrust of the line and the bore weld closes the path for the medium, which is why both welds matter and neither of them is cosmetic. Setting the flange square before welding keeps the bolt holes aligned with the mating flange; a flange pulled off square by weld shrinkage will fight the gasket and leak at the joint face.

Grade 321 carries a titanium addition that ties up the carbon, so the heat affected zone keeps its corrosion resistance after welding and the part holds through thermal cycling. That is why exhaust systems, heat exchanger shells, steam traced lines and furnace area piping reach for 321 rather than a plain 18-8 grade. Because the pipe passes through the flange before welding, the joint tolerates more misalignment than a weld neck and needs less precise pipe cutting, but it also has a lower fatigue rating, so moderate pressure with moderate vibration is its comfortable range. Size, pressure class and facing are confirmed per inquiry, and detailed specifications and drawings are available on request.

FAQ

Q1. How is a slip on flange welded onto the pipe?

The pipe passes through the bore, the flange is set square and tacked, then two fillet welds go on: one at the hub and a second inside the bore. The hub weld carries the thrust, the bore weld seals the medium. Both are structural, so neither is skipped.

Q2. Why choose grade 321 instead of a plain 18-8 stainless?

Grade 321 adds titanium, which ties up the carbon so the welded zone does not sensitise and drop its corrosion resistance. On a line that cycles in temperature, or in hot exhaust and steam traced service, that difference shows up as a joint that keeps its face instead of one that starts to rust.

Q3. Can a slip on flange carry the same load as a weld neck?

Honestly, no. A slip on joint works through two fillet welds and has a lower fatigue rating than a butt welded neck, which suits moderate pressure and moderate vibration. Where the joint sees heavy cycling or high pressure, a weld neck remains the stronger answer.

Q4. What is the smallest order I can place?

Standard flange insulation gasket kits start at one set, and standard gaskets, studs, washers and sleeves start at one piece. Parts made to your drawing or to a non-standard bolt pattern are quoted one by one, because the minimum really depends on the material and the tooling involved.

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