Installation guide · Flanges
Flange joint installation checklist
One page per joint – to print, tick off and file: components to specification, the seven installation steps, an inspection scope based on operators’ guidelines and the documentation with signature. Supplier-neutral – the tightening torque comes from your installation instructions.
- For whom
- Fitters, site managers, quality assurance, purchasing in project business
- Applies to
- metallic pipe flange joints, installed at ambient temperature and depressurised
- What remains binding
- Installation instructions of the gasket and bolt manufacturer, risk assessment and tightening torque of the plant
- How to print
- Print the page (Ctrl + P) – the box column stays empty for ticking; one checklist per flange joint
Joint header data
| Item | Entry |
|---|---|
| Plant · line number · flange joint no. | |
| Nominal size · pressure rating (PN or Class) · standard (EN 1092-1, ASME B16.5 …) | |
| Medium · operating pressure · operating temperature | |
| Installation class according to risk assessment (1 · 2 · 3) | |
| Tightening torque according to installation instructions · lubrication condition it applies to | |
| Fitter · date |
A · Components to specification
Before the first step: is every part what the specification requires – and do the parts match? These points are also what operators’ guidelines have checked later in the sample.
| ☐ | Check point | What matters |
|---|---|---|
| ☐ | Pipe flanges | Type, material, pressure rating and facing (B1/B2, RF …) as specified – marking legible – sealing faces without radial scores, without impact marks, without remains of old gaskets or corrosion |
| ☐ | Gasket | Type, material and size matching the facing and the operating case – dry, not kinked, within its storage time – always new, always single |
| ☐ | Bolts and nuts | Material and strength matching pressure rating and temperature – number, diameter and length according to the flange standard – running freely, replace stiff bolts – metric or inch threads, one system per joint |
| ☐ | Washers | hardened (at least 200 HV, e.g. to ISO 7089) – one per bolt under the nut, two per stud bolt – under the head where the head is turned (blind hole) |
| ☐ | Lubricant | approved for material, temperature and medium (above 250 °C heat-resistant – oxygen only with a lubricant approved for it) – the same lubrication condition for which the tightening torque applies |
| ☐ | Tools | Torque wrench calibrated and set to the torque of the instructions – tightening sequence for the bolt pattern available (see Installing a flange joint) |
B · The seven installation steps
The sequence from our page Gasket installation and bolting as a checklist. The manufacturer’s installation instructions and the plant requirements remain binding – installation by qualified personnel (EN 1591-4).
| ☐ | Step | Done means |
|---|---|---|
| ☐ | 1 Clean and inspect | Sealing faces cleaned (temporary coating removed), visual inspection without findings – rework only decided by a competent person |
| ☐ | 2 Align flanges parallel | Pipework brought into position free of stress – with a gap, trial tightening without gasket at about one tenth of the torque – the flanges come parallel – no chain hoist, no lever, no compensation via the gasket |
| ☐ | 3 Insert the gasket | centred, dry, without adhesive, grease or assembly spray – IBC form centred on the bolts |
| ☐ | 4 Lubricate the bolts | Thread, nut bearing face and – with a turned head – head bearing face lubricated thinly and fully – gasket not touched |
| ☐ | 5 Tighten crosswise in stages | started by hand, then about 30 % → 60–70 % → 100 % of the torque in the sequence of the bolt pattern – check round in turn at full torque until no nut turns any more |
| ☐ | 6 Retighten only when cold | Time fixed (a few hours after installation or after the first heat-up – cooled down and depressurised) – fibre gasket only as long as the joint has not yet seen a temperature above about 100 °C – hot only with its own risk assessment |
| ☐ | 7 Thin, single, new | one gasket, as thin as suitable for flange and operating case – one layer, a new gasket every time |
C · Inspection per installation class
The plant’s risk assessment defines the extent of the inspection via the installation class. The check is made before the leak test with the torque wrench set to the check torque: if the nut does not turn further, the torque has been reached. If a sample deviates, the inspection scope is extended.
| ☐ | Class | Who checks | Scope |
|---|---|---|---|
| ☐ | 1 – lines without special requirements | the fitter himself | self-check, checklist completed |
| ☐ | 2 – lines subject to inspection (e.g. German Industrial Safety Regulation, TA Luft) | second fitter | sample of about 2 % of the joints with check torque |
| ☐ | 3 – lines accepted by an approved inspection body | second fitter and independent person | sample of about 10 %, counter-check about 2 % |
The sample checks at least: components to specification · washers present · bolts lubricated · thread projection two to five turns beyond the nut (DIN 78), with stud bolts about equal on both sides · minimum torque reached.
D · Documentation
| ☐ | Record | Entry |
|---|---|---|
| ☐ | Pipe flange: material · pressure rating · facing | |
| ☐ | Gasket: type · material · size · batch | |
| ☐ | Bolts and nuts: material · size · washers present | |
| ☐ | Lubricant · thread projection (turns) | |
| ☐ | Tightening torque according to instructions · check torque reached | |
| ☐ | Retightening: time · by | |
| ☐ | Installed by · date · signature | |
| ☐ | Checked by (class 2/3) · date · signature |
The tightening torque comes from your installation instructions: table values apply only under the boundary conditions of their source (flange and bolt material, lubrication, gasket group, tightness class) and must be validated by the operator – otherwise it is calculated to EN 1591-1 with gasket parameters to EN 13555, for which the gasket and bolt manufacturers provide software.
E · Dismantling
| ☐ | Step |
|---|---|
| ☐ | Release by operations is given: plant depressurised and flushed, site safety rules observed |
| ☐ | Fitted and attached parts that are not held separately are secured |
| ☐ | Loosening starts facing away from the body and proceeds crosswise – a line under stress can spring out |
| ☐ | Old gasket completely removed, sealing face undamaged – used gasket disposed of, a new one every time |
Frequently asked questions
Why is there no tightening torque in the checklist?
Because it only applies together with materials, lubrication condition, gasket type and tightness class. The torque comes from your installation instructions or from the calculation to EN 1591-1 – the checklist records which torque applied and whether it was reached.
Which flanges does the list apply to?
To metallic pipe flange joints to EN 1092-1 or ASME B16.5, installed at ambient temperature and depressurised. Plastic, enamel and glass flanges follow their manufacturers’ own rules.
Who defines the installation class?
The operator in the plant’s risk assessment – according to medium, pressure, temperature and inspection obligation of the line. The checklist only asks for the class.
Is the checklist available for printing?
This page is the checklist: open the browser’s print view, print one page per joint and file it, filled in, with the plant documentation. It is not enclosed with deliveries.
Inquire about the complete set
Pipe flanges, gaskets, bolts and washers matching each other – as a set per joint, with certificates for each item.
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Status 02.11.2026. Sequence according to our page Gasket installation and bolting – inspection scope, documentation and dismantling summarised in our own words from the VCI guideline on the installation of flange joints in process plants (German Chemical Industry Association, August 2011) – cross-check with the textbook Rohrleitungen (Franke/Platzer). Tightening torques from your installation instructions – German Industrial Safety Regulation, TA Luft and TRBS named as reference.
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