A replacement seal can carry the right nominal size and still be wrong for the tank. For tank builders and repair depots, manlid gasket selection links three questions: what will contact the seal, how the seal responds to compression, and whether its profile fits the closure. Resolving them together gives the replacement a clear service basis.
Chemical compatibility depends on the actual exposure. Record the cargo identity, concentration and temperature alongside the cleaning agents and cleaning cycle. A seal suitable during transport may face different conditions during washing. A broad pH range alone cannot establish suitability for every liquid or mixture.
Direct contact with the core changes the material decision. Plain EPDM is generally unsuitable for mineral-oil fuels, whereas a PTFE-enveloped EPDM seal presents PTFE at its intended cargo-contact surfaces. The distinction matters when comparing materials and when inspecting an envelope for damage that could expose the rubber beneath it.
Food cargoes add a separate material-verification requirement. White colour, a PTFE name or a clean appearance cannot establish food-contact suitability. Obtain documentation covering the exact supplied material and configuration under the intended conditions of use.
Seals containing PTFE can behave differently because PTFE plays different roles in each construction. A PTFE manlid seal may use impregnated reinforced fibres, while a pure PTFE braid uses PTFE yarn. Identifying the construction prevents a cost-conscious impregnated option from being mistaken for a pure-yarn product.
An elastic core addresses the need for recovery after compression. The SUNPASS Super Tank Seal combines a rectangular EPDM core with 100% virgin PTFE covering the top, bottom and inside diameter. Its outer edge may expose EPDM, so this three-sided envelope differs from complete encapsulation. Core support does not remove every creep or leakage risk.
| Construction | Selection significance | Confirmation needed |
| PTFE-impregnated reinforced fibre | Cost-conscious packing construction | Fibre, impregnation and actual cargo duty |
| Pure PTFE braid | PTFE yarn forms the braid | Exact profile and gas-tightness requirement |
| PTFE envelope with EPDM core | Chemical-facing surfaces with elastic support | Envelope condition and permitted exposure |
| FEP-encapsulated elastomer | Jacket enclosing an elastic core | FEP jacket, core compound and profile |
The table distinguishes constructions without ranking them for every cargo. Silicone-core braids are separate configurations, and FEP encapsulated products can use silicone or FKM cores. Neither the core material nor an operating limit should be carried across variants without confirmation.
Nominal diameter identifies a manhole family, not the complete gasket geometry. Super Tank Seal options cover DN300, DN450 and DN500 manholes, with cross-sections including 14 × 10 mm, 14 × 12 mm and 14 × 14 mm. These values must be matched to the individual drawing; they do not establish a universal section for each DN.
Equal nominal sizes can conceal different sealing profiles. In the SUNPASS FEP range, FO00009 and FO00010 are both DN500 with a 486 mm inner diameter. FO00009 has a round 16 mm section; FO00010 has a rectangular 14 × 14 mm section. An FEP FKM O ring therefore needs its own profile and core confirmation.
Braided-seal ordering adds a length distinction. AP00001 has a 14 × 14 mm section and a supplied length of 1625 mm. That length is not its inner diameter. Compare section, ring dimensions or supplied length with the closure drawing, rather than identifying a replacement from the old seal's diameter alone.
Gas tightness depends on the seal and the surrounding closure. Neckring distortion, sealing-face condition and fastener arrangement can affect performance even when the material and dimensions match. Liquid retention alone does not demonstrate suitability for an inert-gas blanket; confirm the specific seal and assembly for that duty.
Pressure and temperature limits belong to the specified operating combination. Check the exact seal grade, cargo, cleaning cycle and complete manlid assembly together. A polymer's material capability does not authorize the same operating limit for the finished closure. Use the equipment maker's approved closure and verification procedure.
Reuse also needs a condition check. Damaged jackets, permanent distortion or poor recovery require attention before the next loading. Follow the operator's inspection and replacement rules; the appearance of a reusable ring does not establish a universal service life.
A manlid replacement may form part of a wider set of ISO tank container spare parts. Alongside Super Tank Seal, the SUNPASS range includes PTFE Manlid Seal and Pure PTFE Manlid Seal. Rubber Seal, O Ring, metal spiral-wound gasket, Pure EPDM Gasket and Natural Rubber Seal options address other specified sealing needs.
Each item still needs its own interface and material match. Combining the supply of these parts does not make different constructions interchangeable in one groove.
Consistent replacement identification benefits from technical review and inspection. SUNPASS supplies tank container manufacturers and serves customers in more than 60 countries. Its technical department includes six experts with over 20 years of industry experience. Eight quality inspectors, each with over five years of experience, cover raw materials, production and finished products. SUNPASS also supplies related tank container sealing products, including Super Tank Seal, PTFE Manlid Seal, Pure PTFE Manlid Seal, Rubber Seal, O Ring, metal spiral-wound gasket, Pure EPDM Gasket and Natural Rubber Seal, so a one-stop order can keep each construction and profile separately specified.
One-stop supply can bring the required seals and related parts together. Keep their drawing references and material specifications distinct so the next depot order repeats the approved configuration.
The useful outcome is a defined material, construction and profile for the next cargo and cleaning cycle. Nominal DN narrows the search; actual dimensions and closure conditions complete it. Recheck that combination when the cargo changes or the seal shows damage.
Discuss your manlid drawing and cargo duty with SUNPASS, a one-stop tank container parts manufacturer with manufacturing roots dating to 1979.
No. PTFE-impregnated reinforced-fibre packing differs from pure PTFE braid. Specify the yarn construction and any core separately; the presence of PTFE alone does not identify the complete seal.
No. DN500 is nominal sizing. Verify the actual ring dimensions and cross-section against the manlid drawing. Round and rectangular sections can share the same nominal designation and inner diameter.
Yes. Reassess the new chemical, concentration, temperature and cleaning exposure against the exact seal construction. Suitability for the previous cargo does not automatically carry over to the next load.
Yes. Cleaning chemicals and temperature form part of the seal's exposure. Include them in the selection review, especially when the cleaning cycle differs substantially from normal transport conditions.
A damaged jacket may expose the underlying elastomer. Remove compromised seals from service and follow the operator's replacement procedure. Confirm the correct replacement configuration before returning the closure to service.
Sunpass Sealing Technology (Zhejiang) Co. LTD
• Zhejiang Top Sealing and Insulation Co.,Ltd.
• Echo Industry Limited
• Tenglong Sealing and Thermal Insulation Manufactory
Add: No. 78 West Road Zhenxing, Lianghui Industry Zone, Yuyao, Zhejiang, China
Tel: +86 574 62837603
E-mail: sales@sealings.cn