Picture this: You are finalizing a purchase order for heat exchanger gaskets, and the spec sheet simply says “double jacket gasket.” Then comes the question you cannot ignore: What are the standard dimensions for double jacket gaskets? The answer is not one single number—it depends on flange size, pressure class, facing type, and the standard you follow. For many ASME B16.5 raised-face flanges, double jacket gaskets follow ASME B16.20, with common thicknesses of 1/8 inch (3.2 mm), inner diameters matched to the flange bore, and outer diameters matched to the raised face or flange seating area. However, heat exchangers, boilers, and non-standard vessels often require custom dimensions. If you order the wrong ID, OD, or jacket thickness, you risk leaks, downtime, and rejected shipments. That is why procurement teams need a clear dimensional reference and a supplier that can confirm every measurement before production. Ningbo Kaxite Sealing Materials Co., Ltd. works with standard and custom double jacket gaskets daily, helping buyers avoid expensive mismatches. In this guide, you will find practical dimension tables, specification tips, and answers to the most common sizing questions.
A double jacket gasket consists of a metal outer shell—usually stainless steel, carbon steel, Monel, or another alloy—with a soft filler such as graphite, PTFE, or ceramic fiber inside. The metal jacket protects the filler and provides resilience under thermal cycling and high pressure. Standard dimensions are defined by three primary measurements: inner diameter (ID), outer diameter (OD), and overall thickness. For pipe flanges, these dimensions are typically aligned with ASME B16.5 or ASME B16.47 flange facing dimensions; for heat exchangers and boilers, they are often tied to the vessel drawing.
Many buyers confuse the flange outer diameter with the gasket outer diameter. The gasket OD must match the raised face diameter or the seating surface, not the flange OD. Likewise, the gasket ID should not protrude into the fluid flow. A small mismatch can cause turbulence, erosion, and premature leakage. The table below breaks down the key dimensional parameters.
| Dimension Parameter | What It Refers To | Common Standard Basis | Typical Example |
|---|---|---|---|
| Inner Diameter (ID) | Bore opening of the gasket; must align with flange bore or tube sheet opening | ASME B16.5 / B16.20, customer drawing | 3.50 in / 88.9 mm for NPS 3 Class 150 |
| Outer Diameter (OD) | Seating width on the flange raised face or groove | ASME B16.5 / B16.20, EN 1514-1 | 5.00 in / 127.0 mm for NPS 3 Class 150 |
| Overall Thickness | Compressed thickness of the jacket and filler | ASME B16.20 common practice | 1/8 in / 3.2 mm |
| Jacket Material | Metal shell grade, corrosion and temperature resistance | ASTM A240, customer specification | 316L stainless steel |
| Filler Material | Soft sealing material inside the jacket | Customer media compatibility | Flexible graphite, PTFE |
Pain point scenario: A procurement engineer in a chemical plant orders a “4-inch Class 300 double jacket gasket” assuming every 4-inch gasket will fit. When the part arrives, the OD is too small because the flange facing type or pressure class changes the seating surface. The production line stops for an extra week.
Solution: Always match the gasket to the exact flange standard, nominal pipe size, and pressure class. Use the representative ASME B16.20 dimension table below as a starting point, but confirm every value with your supplier before release.
| Nominal Pipe Size (NPS) | Pressure Class | Typical Gasket ID (in / mm) | Typical Gasket OD (in / mm) | Thickness (in / mm) | Common Filler |
|---|---|---|---|---|---|
| 1 | 150 | 1.31 / 33.3 | 2.00 / 50.8 | 0.125 / 3.2 | Graphite |
| 2 | 150 | 2.38 / 60.5 | 3.62 / 91.9 | 0.125 / 3.2 | Graphite |
| 3 | 150 | 3.50 / 88.9 | 5.00 / 127.0 | 0.125 / 3.2 | Graphite |
| 4 | 300 | 4.50 / 114.3 | 6.19 / 157.2 | 0.125 / 3.2 | Graphite |
| 6 | 300 | 6.63 / 168.4 | 8.50 / 215.9 | 0.125 / 3.2 | Graphite |
| 8 | 300 | 8.63 / 219.2 | 10.62 / 269.7 | 0.125 / 3.2 | Graphite |
The values above are representative examples for raised-face flanges. For flat-face flanges, large-diameter flanges, or tongue-and-groove joints, the OD and thickness may change significantly. Ningbo Kaxite Sealing Materials Co., Ltd. can provide a dimension drawing for approval before manufacturing.
Pain point scenario: Your maintenance team sends a photo of an old gasket with a ruler next to it. The supplier receives the photo but cannot read the exact ID, OD, or thickness. The quotation gets delayed, and you are pushed to accept an estimated size that may not fit.
Solution: Create a standard specification sheet with six to eight data points. If you do not have a drawing, send the old gasket or a detailed sketch. The following table shows the minimum parameters a supplier needs to produce an accurate double jacket gasket.
| Parameter | What to Specify | Example |
|---|---|---|
| Gasket ID | Inner diameter or flange bore size | 350 mm / 13.78 in |
| Gasket OD | Outer diameter or raised face diameter | 410 mm / 16.14 in |
| Overall Thickness | Total compressed thickness | 3.2 mm / 0.125 in |
| Jacket Material | Grade of metal jacket | 316L stainless steel |
| Filler Material | Soft filler type | Flexible graphite |
| Temperature / Pressure | Operating conditions | 250°C / 40 bar |
| Tolerance | Acceptable deviation on ID and OD | ±0.5 mm ID, ±0.8 mm OD |
| Quantity | Number of pieces and delivery date | 20 pcs, 4 weeks |
When these details are clear, a qualified gasket manufacturer can produce the correct part on the first attempt. Ningbo Kaxite Sealing Materials Co., Ltd. offers pre-production drawings for standard and custom double jacket gaskets, so you can approve dimensions before cutting.
Q: What are the standard dimensions for double jacket gaskets under ASME B16.20?
A: For standard raised-face flanges, double jacket gasket dimensions follow the flange seating surface. The most common thickness is 1/8 inch (3.2 mm). The inner diameter generally matches the flange bore or pipe inner diameter, and the outer diameter matches the raised face diameter for the specified NPS and pressure class. For example, a NPS 3 Class 150 raised-face flange typically uses a gasket with an ID around 3.50 inches and an OD around 5.00 inches. Always confirm because the OD changes with pressure class, flange facing, and standard revision.
Q: What are the standard dimensions for double jacket gaskets when my flange is non-standard or belongs to a heat exchanger?
A: There is no universal standard dimension for non-standard or heat exchanger double jacket gaskets. The required ID, OD, thickness, and cross-section depend on the groove design, tube sheet layout, and original equipment manufacturer drawing. In these cases, provide a dimensioned drawing, old gasket sample, or detailed sketch. Ningbo Kaxite Sealing Materials Co., Ltd. can manufacture custom double jacket gaskets from customer drawings and can also help reverse-engineer dimensions from a used gasket.
Pain point scenario: A buyer receives three quotations, but two suppliers do not confirm dimensions. One quotes a lower price but uses a different OD. The buyer chooses the cheap option, and the gasket leaks during hydrotesting. The cost of downtime is far higher than the savings on the gasket.
Solution: Work with a sealing manufacturer that treats dimensional accuracy as a quality control step, not an afterthought. Ningbo Kaxite Sealing Materials Co., Ltd. supplies double jacket gaskets in standard ASME B16.20 sizes and fully custom configurations. The company reviews each inquiry against flange standards, confirms materials, and provides production drawings when required. This reduces the risk of ordering the wrong size and helps you avoid costly downtime. With years of experience serving industrial buyers, Ningbo Kaxite Sealing Materials Co., Ltd. understands that procurement teams need clear answers, fast quotes, and reliable dimensional data.
Double jacket gasket dimensions are not guesswork. They require the correct flange standard, NPS, pressure class, facing type, ID, OD, and thickness. When any one of these parameters is missing, the risk of leakage and unplanned shutdown increases. Use the tables and specification checklist in this guide as your starting reference, and always verify dimensions with your supplier before releasing a purchase order.
Ningbo Kaxite Sealing Materials Co., Ltd. is a professional manufacturer and supplier of sealing materials, specializing in double jacket gaskets, spiral wound gaskets, ring joint gaskets, and other industrial sealing products. The company supports standard and custom dimensions, offers material certification, and helps procurement teams confirm the correct size before production. For a fast quote or to send a drawing for review, contact the team at [email protected]. Let Ningbo Kaxite Sealing Materials Co., Ltd. solve your double jacket gasket dimension problem and keep your flanges sealing reliably.
Abid, M., & Nash, D. H., 2004, Comparative study of the behaviour of conventional gasketed and non-gasketed bolted flange joints under combined internal pressure and bending, International Journal of Pressure Vessels and Piping, Vol. 81, No. 8.
Bouzid, A.-H., & Chaaban, A., 1997, An accurate method of evaluating relaxation in bolted flanged connections, Journal of Pressure Vessel Technology, Vol. 119, No. 1.
Fukuoka, T., & Takaki, T., 2004, Finite element simulation of bolt-up process of pipe flange connections with spiral wound gasket, Journal of Pressure Vessel Technology, Vol. 126, No. 4.
Murali Krishna, M., Shunmugam, M. S., & Siva Prasad, N., 2007, A study on the sealing performance of bolted flange joints with gaskets using finite element analysis, International Journal of Pressure Vessels and Piping, Vol. 84, No. 6.
Nagata, S., & Sawa, T., 2008, Effects of scatter in bolt preload on sealing performance of pipe flange connections with gaskets, Journal of Pressure Vessel Technology, Vol. 130, No. 1.
Nelson, N. R., & Prasad, N. S., 2009, Sealing performance of gasketed bolted flange joints under combined internal pressure and thermal loading, International Journal of Pressure Vessels and Piping, Vol. 86, No. 6.
Sawa, T., & Maruyama, K., 2004, Sealing performance of pipe flange connections with gaskets under internal pressure, Journal of Pressure Vessel Technology, Vol. 126, No. 1.
Abid, M., & Iqbal, J., 2011, Determination of optimized bolt preload for gasketed flange joints, Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, Vol. 225, No. 3.
Brown, W., & Marchand, L., 2006, Effect of gasket thickness on the sealing performance of bolted flange joints, ASME Pressure Vessels and Piping Conference, Vol. 475.
Kazeminia, M., & Bouzid, A.-H., 2009, Evaluation of gasket contact stress distribution in bolted flange joints using finite element analysis, Journal of Pressure Vessel Technology, Vol. 131, No. 4.
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