How do you calculate valve leakage rework rate?

Divide the valves reworked for leakage by the total valves leak-tested, then multiply by 100. With 7 reworked out of 200 tested, that is 7 / 200 x 100 = 3.5%.

What is a good leakage rework rate for a valve test line?

Mature gate and globe lines run 1-3%; precision control and cryogenic valves can hold under 1%. At 3.5% against a 3% target you are 0.5 points over and should investigate seat lapping or actuator torque.

Does this count both seat and shell leakage failures?

Yes — it counts any valve reworked because it failed a leakage criterion, whether seat (API 598/FCI 70-2) or shell/body. Track them separately if the mix is shifting.

Why is my gap to target negative?

A negative gap means you are below target, which is good. The example shows -0.5 points only when you beat the target; with these defaults the rate of 3.5% versus a 3% target gives a +0.5 over-target gap.

Rework rate vs. scrap rate — what is the difference?

Rework rate captures valves that can be salvaged by re-lapping or re-seating; scrap rate counts valves that fail beyond recovery. A valve can be reworked several times before it becomes scrap.

How can I lower leakage rework on seat tests?

Tighten seat flatness and surface-finish control during lapping, verify seat-ring concentricity, confirm correct seating torque on actuated valves, and audit soft-seat material storage for swelling or contamination.

Industrial Valves, Actuators & Flow Control calculator

Rework Rate from Leakage Failures Calculator

Leakage rework rate tells a valve shop what fraction of seat and shell leak tests fail badly enough to send the valve back for re-lapping, re-seating, or re-machining. Quality engineers and test-bench supervisors on gate, globe, ball, and control valve lines track it as a direct readout of upstream machining, lapping, and assembly discipline. A climbing rework rate burns bench capacity, delays witnessed hydro and pneumatic tests, and quietly inflates per-valve cost. Watching it against a target rate keeps the test cell from becoming the plant bottleneck.

What this calculator does

Calculate your valve rework rate caused by seat or shell leakage test failures and measure the gap to your quality target. Helps identify whether lapping, re-machining, or seal replacement processes need improvement.
Use this when tracking rework caused by leakage failures during production testing, reporting quality KPIs, or deciding whether to invest in lapping equipment or tighter machining tolerances.
It divides valves reworked for leakage by total valves leak-tested in the period to give a rework percentage, then compares it to your target.

Formula used

Leakage rework rate = reworked valves / total valves tested x 100
Gap to target = rework rate - target rework rate (negative means you are meeting target)

Inputs explained

Valves reworked after failing seat or shell leakage test:
Total valves seat/shell leak-tested this period:
Target leakage rework rate:

How to use the result

Use it weekly or per lot to monitor seat/shell test yield on a valve assembly and test line and to flag when machining or lapping quality is drifting.
It counts any leakage rework equally, so a single drop-past-the-seat reject weighs the same as a scrapped body casting — segment by failure mode before acting.

Current U.S. benchmarks

The U.S. has 21,668 machinery manufacturing establishments employing about 1,086,146 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate valve leakage rework rate? Divide the valves reworked for leakage by the total valves leak-tested, then multiply by 100. With 7 reworked out of 200 tested, that is 7 / 200 x 100 = 3.5%.
What is a good leakage rework rate for a valve test line? Mature gate and globe lines run 1-3%; precision control and cryogenic valves can hold under 1%. At 3.5% against a 3% target you are 0.5 points over and should investigate seat lapping or actuator torque.
Does this count both seat and shell leakage failures? Yes — it counts any valve reworked because it failed a leakage criterion, whether seat (API 598/FCI 70-2) or shell/body. Track them separately if the mix is shifting.
Why is my gap to target negative? A negative gap means you are below target, which is good. The example shows -0.5 points only when you beat the target; with these defaults the rate of 3.5% versus a 3% target gives a +0.5 over-target gap.
Rework rate vs. scrap rate — what is the difference? Rework rate captures valves that can be salvaged by re-lapping or re-seating; scrap rate counts valves that fail beyond recovery. A valve can be reworked several times before it becomes scrap.

Last reviewed 2026-05-12.