Short answer: a kammprofile gasket with a loose outer ring is a solid machined metal core with concentric serrations on both faces, faced with graphite or PTFE, and enclosed by a removable locating ring that is not welded or machined into the sealing element. Compared with the integral-ring version, the loose ring can be swapped or replaced separately, and the serrated core can be re-faced and re-used across maintenance cycles rather than scrapped as one piece.
The three kammprofile constructions use the same serrated metal core; the difference is how the outer locating ring is attached and what that means for maintenance, cost and lead time.
| Construction | Outer ring | Best for | Maintenance | Relative cost |
|---|---|---|---|---|
|
Loose outer ring (this page) |
Separate removable part | Flanges with narrow seating, or where the core will be refurbished and re-used | Ring and core can be replaced independently; core re-facable | Mid — but lower lifetime cost due to re-use |
| Integral outer ring | Machined from the same blank | Standard ASME B16.20 flanges; simplest installation | Whole gasket replaced each cycle | Standard |
| Basic style (no ring) | None | Tongue-and-groove or male-and-female flanges | Core can be re-faced | Lowest |
Centres the serrated core on the flange bolt circle and limits compression before the serrations are crushed. The ring is dimensioned to the flange standard and slips around the core without being welded.
Material optionsSolid machined ring with concentric serrations on both faces. The serrations concentrate bolt load onto narrow contact lines, sealing with far lower stress than a spiral wound gasket while remaining blow-out resistant.
Core materialsExchanger joints are opened at every turnaround. Re-facing the core and reusing the loose ring cuts the replacement cost on the largest sizes where the metal alone is expensive.
Steam flanges above 40 bar. The serrations seal at low bolt load and hold against thermal cycling without the spiral wound gasket's risk of buckling.
Flanges where the seating face is too narrow for a spiral wound gasket with inner and outer rings. The loose ring sits behind the seating area without interfering.
Hydrogen, sour gas and hydrocarbon service where graphite-faced kammprofile outperforms spiral wound construction and fire-safe documentation is mandatory.
For high-pressure compact pipe flanges that accept a standard ASME spiral wound gasket, compare our spiral wound gasket range. For ring-type joints on wellheads and high-pressure gas service, see ring joint gaskets. For very large low-bolt-load flanges, the corrugated metal gasket is often the more economical construction.
The serrated core, the loose ring and the graphite or PTFE facing are all produced or applied in our own workshop in Zhenhai, Ningbo. We also operate a re-facing line for returning kammprofile cores — an option most trading companies cannot offer.
We ship to refinery maintenance contractors, petrochemical EPC firms, valve OEMs and industrial distributors across Europe, the Middle East, Southeast Asia and South America. Third-party pre-shipment inspection by SGS, BV or TÜV can be arranged. FOB Ningbo or Shanghai is standard; CIF, CFR and DDP quoted on request.
Same serrated core, different ring attachment. Integral = ring machined from the same blank, one piece. Loose = separate removable ring. Loose allows ring and core to be replaced independently and lets the core be re-faced and re-used; integral is simpler but the whole gasket is scrapped each cycle.
MOQ 10 pcs for standard ASME sizes. Production lead time 7–15 days after size or drawing confirmation. Non-standard outlines add 3–5 days for CNC programming.
SS316L for general refinery and steam service. SS321 / SS347 where intergranular corrosion is a concern. Monel 400 for seawater and HF. Inconel 625/825 and Hastelloy C276 for severe chloride and high-temperature oxidation. Send the medium and we confirm in writing.
Yes — the serrated core is solid and can be cleaned, re-serrated and re-coated with new graphite or PTFE facing. Only the facing (and the loose ring, if damaged) is replaced, not the whole assembly.
Graphite-faced grades are available with API 607 and ISO 10497 documentation. PTFE-faced grades are not fire-safe by nature. State the requirement at quotation stage so the correct grade is scheduled.
Core material test certificate, dimensional inspection report and packing list are standard. Third-party inspection (SGS, BV, TÜV) can be arranged if your QA team requires it.
Standard ASME or drawing. Include the flange class, medium, temperature and pressure. Price, MOQ, lead time and facing recommendation returned within 8 working hours.
Request a QuoteAddress
No 432 Zhenhai Middle Road, Luotuo Street, Zhenhai District, Ningbo City, Zhejiang China
