How do you calculate hydrotest capacity?

Multiply units per cycle by available cycles to get gross capacity, then multiply by uptime and first-pass yield. With 4 units per cycle, 480 cycles, 90% uptime and 97% yield, gross is 1,920 units and good output is about 1,676 units.

What is the difference between gross and good hydrotest capacity?

Gross capacity is the theoretical maximum if the bay ran perfectly. Good capacity subtracts downtime and re-tests: in the default, 192 units are lost to uptime and about 52 to yield failures, leaving 1,676 shippable.

What is a good first-pass hydrotest yield?

Mature vessel shops often run 95 to 99 percent first-pass on hydrotest because most weld defects are caught earlier by RT or PT. The 97% default is realistic; a yield below 90% signals upstream welding or fit-up problems, not a test-bay issue.

How do I increase hydrotest throughput without a second bay?

Attack uptime and yield first. Reducing changeover between fills, staging blind flanges and gaskets ahead of time, and cutting re-tests through better upstream NDE all raise good output before you invest in a second station.

Why does uptime matter so much for a test bay?

Hydrotest cycles are long, so every point of downtime removes whole vessels from the plan. Here 90% uptime alone costs 192 units against gross - more than three times the yield loss - which is why pumps, gauges and drain systems should be on a preventive maintenance schedule.

Does this account for hold-time requirements in the code?

Only indirectly, through units per cycle. If your code or customer spec requires a longer minimum hold, fewer vessels fit per cycle, so lower the units-per-cycle input rather than adjusting the yield or uptime.

Tank, Vessel & Pressure Equipment Fabrication calculator

Hydrotest Capacity Calculator

Hydrotest Capacity estimates how many tanks or pressure vessels your hydrostatic test station can actually pass in a given period, after accounting for downtime and first-pass failures. Hydrotesting is a common bottleneck in vessel shops because fill, pressurize, hold, inspect and drain cycles are slow and often gate final shipment. Production planners and shop managers use this to see whether test-bay throughput can keep up with fabrication and to spot when a second bay or a longer shift is needed. The gap between gross and good capacity is exactly where schedule slips hide.

What this calculator does

Hydrotest Capacity estimates how many tanks or pressure vessels your hydrostatic test station can actually pass in a given period, after accounting for downtime and first-pass failures.
Use it when hydrotest capacity in tank, vessel and pressure equipment fabrication is being asked to take on more work and you need to know if there is room.
It converts units per cycle and available cycles into gross capacity, then applies uptime and first-pass yield to give realistic good-vessel throughput.

Formula used

Gross hydrotest capacity capacity = units per cycle × available cycles
Good capacity = gross capacity × uptime × yield

Inputs explained

Vessels hydrotested per test cycle:
Available test cycles in the period:
Test-bay uptime:
First-pass hydrotest yield:

How to use the result

Use it when planning shop loading, quoting delivery dates, or deciding whether the hydrotest station is your constraint.
It assumes uniform vessel size and a fixed cycle; a run of large or multi-chamber vessels will consume more of each cycle than the average implies.

Current U.S. benchmarks

U.S. iron and steel imports ran $2.1B in May 2026 (Census International Trade). The U.S. ran a trade deficit of $0.4B in the category that month. Import volumes are the pressure gauge behind tariff and reshoring decisions.
Steel mill PPI stands at 348.53 (BLS, May 2026), up 6.7% from a year earlier. New factory orders are up 2.3% year over year (Census).
The U.S. has 53,790 fabricated metal products establishments employing about 1,441,471 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate hydrotest capacity? Multiply units per cycle by available cycles to get gross capacity, then multiply by uptime and first-pass yield. With 4 units per cycle, 480 cycles, 90% uptime and 97% yield, gross is 1,920 units and good output is about 1,676 units.
What is the difference between gross and good hydrotest capacity? Gross capacity is the theoretical maximum if the bay ran perfectly. Good capacity subtracts downtime and re-tests: in the default, 192 units are lost to uptime and about 52 to yield failures, leaving 1,676 shippable.
What is a good first-pass hydrotest yield? Mature vessel shops often run 95 to 99 percent first-pass on hydrotest because most weld defects are caught earlier by RT or PT. The 97% default is realistic; a yield below 90% signals upstream welding or fit-up problems, not a test-bay issue.
How do I increase hydrotest throughput without a second bay? Attack uptime and yield first. Reducing changeover between fills, staging blind flanges and gaskets ahead of time, and cutting re-tests through better upstream NDE all raise good output before you invest in a second station.
Why does uptime matter so much for a test bay? Hydrotest cycles are long, so every point of downtime removes whole vessels from the plan. Here 90% uptime alone costs 192 units against gross - more than three times the yield loss - which is why pumps, gauges and drain systems should be on a preventive maintenance schedule.

Last reviewed 2026-05-12.