Pre-start-up testing
Hydrotest Planning After a Shutdown: Leak Test Register and Checks
Hydrotest planning lists every repaired or reassembled system as a test pack, places the test late in the schedule with float for a leak, prepares each system and records the result and the reinstatement of every blind and gag. The code and your engineer set the test pressure and hold. MaintWiz holds test and reinstatement checks on the work order.
STO means shutdown, turnaround and outage. This page covers planning only; follow the applicable code, your engineer and your procedure for the test itself.
How MaintWiz helps: Tests come last, so any delay lands on the restart date. The MaintWiz shutdown module checks seven readiness gates before a package starts and records waivers with a typed reason, name and date. See the module · Get the test register
By Jai Balachandran · Published · Last reviewed
What MaintWiz adds:Seven readiness gatesSigned waivers with name and dateKeyboard operationLook-ahead by gate
Definition
What is hydrotest and leak test planning after a shutdown?
Hydrotest and leak test planning decides which repaired or reassembled systems need a strength test or a tightness test before restart, sequences the tests in the schedule, prepares each system, and records the result and the reinstatement of everything fitted for the test. In this guide STO means shutdown, turnaround and outage.
Repairs, alterations, new gaskets and replaced bundles all break the last proof that a system holds. The test is how you regain it. Tests come late in the schedule, so any delay or leak found there lands directly on the restart date. A planned register keeps them from becoming the surprise at the end of the stop.
This page covers planning. The test method, pressure and hold are set by the applicable code and your engineer; follow them. Download the free hydrotest and leak test register (Excel) to track every test pack.
Test types
What is the difference between a hydrotest and a leak test?
A hydrotest is a strength test that proves the pressure boundary at the pressure the code and engineer set, while a leak test proves joints are tight before start-up, and a pneumatic test is an exception that needs engineering approval because it stores much more energy.
| Test | Purpose | Planning note |
|---|---|---|
| Hydrostatic strength test | Prove the pressure boundary at the test pressure the code and engineer specify | Uses water. Needs fill, vent, temperature and drain plans |
| Leak or tightness test | Prove joints and connections are tight before start-up | Often at lower pressure. Method per procedure |
| Pneumatic test | Used only where water is not acceptable | Stores far more energy than a hydrotest. Needs engineering approval and a specific risk assessment |
| Pressure systems regulation checks | Examinations required where regulations apply; see start-up after a shutdown 3 | Link the test to the written scheme where one exists |
Pressure vessel and piping inspection codes such as API 510 and API 570 set requirements for tests after repair or alteration. Check the current edition. 1
MaintWiz
How does MaintWiz track pre-start-up tests?
MaintWiz puts test and reinstatement checks on the work order as checklists with readings and photos and holds the package closed until the permit and isolation are cleared; AI agents support shutdown planning.
Bring a test pack list to a demo and we will set it up as a checklist. Tell us what your inspectors sign: plant requirements shape what we build next.
About MaintWiz. MaintWiz is an industrial AI platform with IoT, SAP integration and predictive maintenance (PdM) capabilities. Its shutdown and turnaround module helps plants plan, schedule, execute and close out shutdown work.
What the shutdown module covers
As described on the MaintWiz shutdown maintenance product page.
- Readiness gates that include tests and reinstatement
- Permits and isolations shown on each work order
- Checklists with readings and photos for technicians
- Gantt chart with critical path, float and baselines
- Findings from technicians sent straight to the planner
- Handover notes and as-left summary
Proof
What MaintWiz customers report
Figures as published in MaintWiz case studies on maintwiz.com. They come from maintenance management projects, not shutdowns.
Plan
How do you plan hydrotests in a shutdown schedule?
Plan hydrotests by listing every repaired or reassembled system as a test pack, placing each test late in the sequence after repairs and before insulation or restart, adding float for leaks found, and booking the water, witnesses and exclusion zone ahead of time.
- 1
List test packs
One per system or equipment with its boundary and drawing.
Register - 2
Get the approved pack
Test type, pressure and hold from the engineer and code.
Approval - 3
Place it in the schedule
After repairs, before insulation and restart, with float for a failure.
Sequence - 4
Book the resources
Water supply, pump, gauges, witness and an exclusion zone.
Resources - 5
Prepare the system
Blinds, gagged relief valves, vents, drains, instruments isolated.
Preparation - 6
Run, record, reinstate
Test, drain, remove every fitting, restore, sign off.
Close
Put tests that gate restart on the critical path view. See shutdown scheduling.
Checks
What should you check before a hydrotest?
Before a hydrotest confirm the approved test pack, list and fit the boundary blinds, gag or remove relief valves and record them, isolate instruments, confirm high-point vents and low-point drains, and make sure the water suits the materials and the metal temperature suits the procedure.
| When | Check |
|---|---|
| Before filling | Approved test pack in hand. Boundary blinds fitted and listed. Relief valves gagged or removed, and listed. Instruments isolated. Vents at high points and drains at low points confirmed. Water quality suitable for the materials |
| During the test | Exclusion zone set. Fill and vent. Check temperature of the metal against the procedure. Pressurize in steps. Hold as specified. Witness present |
| After the test | Depressurize through the vents first. Drain and dry if required. Remove blinds. Restore relief valves and instruments. Update the register. Sign off |
Reinstatement belongs in the restart check. See start-up after a shutdown 2.
Common misses
What goes wrong in turnaround pressure tests?
The common misses are a blind or gag left in after the test, a vent not opened so a vacuum forms on draining, trapped water that expands, unsuitable water for stainless materials, a test pack without an approved pressure and tests scheduled with no float for a leak.
Blind or gag left in
List every item fitted for the test and tick each one off at reinstatement.
Water problems
Wrong quality for the material, or trapped water that expands. Plan drains and quality.
No float
A leak found at the end moves the restart. Add float and a repair crew on standby.
No approved pack
Do not test to a pressure that is not in an approved pack.
Visuals
Save the pressure test planning visuals
Two visuals for the test coordinator. Click either for the full-size image.
FAQ
Frequently asked questions
What is a hydrotest?
A hydrostatic strength test that fills a system with water and raises it to the pressure the code and engineer specify to prove it holds.
What is the difference between a hydrotest and a leak test?
A hydrotest proves the pressure boundary at the specified test pressure. A leak test proves joints are tight before start-up, often at a lower pressure.
When is a pressure test needed after a shutdown?
After repairs, alterations, replaced components or reassembly that affect the pressure boundary, as the applicable code and your engineer require.
Where does a hydrotest sit in the shutdown schedule?
After the repairs and before insulation and restart, with float for a leak, and on the critical path where it gates restart.
Why avoid a pneumatic test?
A gas-filled system stores much more energy than a water-filled one. Use it only with engineering approval and a specific risk assessment.
What is the most common hydrotest mistake?
Leaving a blind or gagged relief valve in place after the test, so keep a list and tick off each one at reinstatement.
Who sets the test pressure?
The applicable code and the responsible engineer, recorded in the approved test pack.
Is there a free hydrotest register?
Yes. The hydrotest and leak test register (Excel) tracks each test pack, its preparations, the result and the reinstatement.
Does MaintWiz track tests before restart?
It holds test and reinstatement checks on the work order and keeps the package open until the permit and isolation clear. AI agents are part of the module. See AI shutdown planning.
Sources
Sources
This page gives planning practice and no test pressures. Use the code, your engineer and your procedure. API standards are listed on the API site; the OSHA and HSE pages cover pre-start-up review and pressure systems.
Start each package only when it is ready
Book a demo and bring a work package. We will walk through the seven readiness gates.