Colour: the winding
The outside edge of the centering ring is painted one solid colour for the metal of the spiral windings: yellow 304, green 316L, turquoise 321, orange Monel 400.
Reference tool — not inspection
Read the gasket before it goes in an RFQ.
Spiral wound gasket
Colours or marking.
Pick the edge colour and the stripes, or switch to the marking. In the marking view, below the examples, an offered replacement’s marking can be checked against it: size, class, winding, filler and rings. The drawing and the RFQ line update with every change.
Examples:
Replacement check
On the markings alone: the flange standard, the gasket drawing and the service conditions decide.
All 130 engineering tools
A spiral wound gasket carries its materials on the outside edge of the centering ring: under the ASME B16.20 colour code a solid colour shows the winding metal and stripes the filler. Pick the colours you see, or type the marking stamped on the ring, and the reader names the materials, says when B16.20 requires an inner ring and writes the RFQ line.
Colours are a code, not proof: the stamping on the ring and the maker’s certificate confirm the materials.
How the code is read
Edge colour, stripes, stamp.
Stripes: the filler
Stripes at equal intervals on the same edge show the filler between the windings: grey flexible graphite, white PTFE, light green ceramic.
Stamp: the rings
The centering ring and any inner ring are stamped with their material, size and class. White and gold each stand for two alloys, so the stamp settles those too.
| Winding metal | Colour on the edge | Marked as |
|---|---|---|
| 304 stainless steel | Yellow | 304 |
| 316L stainless steel | Green | 316L |
| 317L stainless steel | Maroon | 317L |
| 321 stainless steel | Turquoise | 321 |
| 347 stainless steel | Blue | 347 |
| Carbon steel | Silver | CRS |
| Alloy 20 (20Cb-3) | Black | A-20 |
| Hastelloy B2 | Brown | HAST B |
| Hastelloy C276 | Beige | HAST C |
| Incoloy 800 | White | IN 800 |
| Incoloy 825 | White | IN 825 |
| Inconel 600 | Gold | INC 600 |
| Inconel 625 | Gold | INC 625 |
| Inconel X750 | No colour | INX |
| Monel 400 | Orange | MON |
| Nickel 200 | Red | NI |
| Titanium | Purple | TI |
| Filler | Stripes | Marked as |
|---|---|---|
| PTFE | White | PTFE |
| Flexible graphite | Grey | F.G. |
| Ceramic | Light green | CER |
Abbreviations as Garlock gives them; other makers’ forms differ, and the reader takes the common variants. Metals outside the table, such as 304L, are identified by the stamp.
Inner ring
ASME B16.20 requires an inner ring with PTFE filler, and in Class 900 from NPS 24, Class 1500 from NPS 12 and Class 2500 from NPS 4. With flexible graphite filler one is furnished unless the purchaser specifies otherwise.
Sources
Colours and abbreviations: Garlock, "Spiral Wound Specifications" (sheet D-19, colour columns marked as the ASME B16.20 standard), and Flexitallic’s guide to guide ring colour coding; both give the same colour for every metal and filler in the tables. Inner rings: ASME B16.20 as quoted in Garlock’s technical bulletin, and Wermac’s summary of the standard.
Before you send the gasket
Questions about gaskets in an RFQ
What does a green gasket with grey stripes mean?
A spiral wound gasket with 316L stainless steel windings and flexible graphite filler. Under the ASME B16.20 colour code the solid colour on the outside edge of the centering ring shows the winding metal, and the stripes the filler.
Does the colour show the centering ring material?
No. The colours show only the winding metal and the filler; the centering ring and inner ring materials are stamped on the ring. White stands for both Incoloy 800 and 825, and gold for both Inconel 600 and 625, so those need the stamping too.
When is an inner ring required?
ASME B16.20 requires an inner ring with PTFE filler, and in Class 900 from NPS 24, Class 1500 from NPS 12 and Class 2500 from NPS 4. With flexible graphite filler one is furnished unless the purchaser specifies otherwise.
What should the request include?
The NPS and class, the flange standard (ASME B16.5, or B16.47 Series A or B), the winding metal, the filler, the centering ring and inner ring materials and the quantity. A photograph of the ring edge and the stamping settles what the colours leave open.
Gasket read?
Send the line with the photographs.
Colours and a decoded marking are a cross-check, not proof. Attach photographs of the ring edge and the stamping, and Vessel Core checks them against each other before an offer goes back.
Buyer tools
