This guide is for maintenance teams and buyers who need a new gasket for a flange and have no part number. It shows which measurements to take, how to take them and what to send us. A clear set of measurements saves a wrong order and a second visit to the machine.
What our catalogue lists
Our catalogue lists gaskets as custom gasket materials for flange sealing, machinery, piping and industrial maintenance. It also lists rubber sheets, which are described for flooring, lining, sealing and protection.
Our catalogue lists gaskets as custom, so a gasket order starts with your measurements. Tell us what you have measured and we will confirm what we can offer. The industrial materials page shows the full range.
Before you measure
Measure only a joint that is open and safe to work on. Follow your site rules and your safety officer for opening pipework and equipment.
Have these ready:
- A steel rule or tape, and a calliper if you have one.
- A pen and paper, or your phone for photos.
- The old gasket, even if it is cracked, hardened or in pieces.
Write every number with its unit. Millimetres are best. Measure twice, and write down both readings if they differ.
The five measurements
Look at the flange face first. Your gasket may sit inside the bolts as a ring, or it may cover the whole face and have its own bolt holes. Tell us which one you have.
Then take these measurements:
- Inner diameter. This is the size of the opening in the middle of the gasket. If the old gasket is whole, measure it. If not, measure the opening on the flange face.
- Outer diameter. For a ring gasket, measure across the outside edge of the gasket. For a full face gasket, measure across the whole flange face.
- Number of bolt holes. Count them and write the number down.
- Bolt hole diameter. Measure the width of one hole, and check that the others match.
- Bolt circle. Measure from the centre of one hole to the centre of the hole opposite it. This is the bolt circle diameter.
If the number of holes is odd, there is no hole directly opposite. Send us a photo with a rule laid beside the flange, or send the old gasket.
When the old gasket is damaged or gone
A drawing, a photo or the old gasket can all help. Send what you can supply.
- The old gasket. Send it, or lay it flat on paper and trace round the outside and the bolt holes. Keep the tracing flat.
- A photo. Take it straight on, with a rule or tape in the picture. Do not take it at an angle.
- A drawing. A hand sketch with the measurements written on it helps.
If the old gasket is flattened or swollen, tell us. Measure its thickness if you can, and say what you see.
Also tell us if the flange face is not flat or is badly marked. We cannot see this from a drawing.
A short check can save a wrong order. Before you send the numbers, confirm four points:
- The inner and outer diameters are in the same unit, and the bolt circle is written down.
- The bolt hole count and the bolt circle match the flange.
- Every number has its unit next to it.
- The photo shows the whole flange face, with a rule in view.
If you have two flanges of the same size on one machine, measure both. Do not assume that their sizes are the same.
Choose the material and thickness together
The measurements give us the shape. The material and the thickness depend on your job, so tell us about it.
Our catalogue does not say which material a gasket is made from, so tell us about the joint. For example, our catalogue describes nitrile as oil-resistant NBR rubber sheet for workshops, gaskets, pads and fuel-related environments.
Tell us what the joint carries, such as water, oil, fuel or a chemical, and how hot it gets. Tell us the thickness of the old gasket, if you know it. We will confirm the material and thickness for your joint. For a pump housing or a machine cover, see gaskets for pumps and machinery covers.
What to send us for a quote
- Whether the gasket is a ring or a full face gasket.
- Inner diameter and outer diameter, with units.
- Number of bolt holes, hole diameter and bolt circle diameter.
- The thickness of the old gasket, if you know it.
- What the joint carries and the operating conditions.
- A drawing, photos with a rule in view, or the old gasket.
- The quantity you need.
Request a quote on our website or message us on WhatsApp, and we will confirm the right material for your joint.