Thread seal tape types
There are two US standards to determine the quality of any Teflon tape. MIL-T-27730A (obsolete military specification is still commonly used in the industry in the United States) the minimum required thickness of 3.5 mils and 99% minimum purity PTFE.  The second standard, AA-58092,  is a commercial grade which maintains MIL-T-27730A thickness requirements, and increased minimum density of 1.2 g / cm 3  of the relevant industry standards may Changes between. ; Tape gas fitting (UK gas regulations), need to be thicker than water. Although Teflon itself is suitable for use with high-pressure oxygen level it must be known to the tape free of grease.
Seal used in pipeline applications is the most common white, but it is also a different color available. White Teflon is a single density, yellow and pink triple double. It is often used to correspond to the color-coded pipes (United States, Canada, Australia and New Zealand: yellow for the natural gas, green is oxygen, etc.). These color codes thread seal tape is Unasco Pty Ltd Bill Bentley in the 1970s introduced. In the UK, the tape is from colored scrolls, for example, using yellow reel gas, green for the drinking water.
White – for 3/8 inch NPT thread
Yellow – for NPT thread 1/2 inch to 2 inches, often labeled “air band”
Pink – for NPT thread 1/2 inch to 2 inches, safety hydrocarbons such as propane fuel
Green – oxygen line and a number of specific medical gas oil free PTFE
Ash – containing nickel, anti-sintering, anti gailling and corrosion for stainless steel pipe
Copper – containing copper particles and is certified as a lubricant instead of thread-sealing machine
In Europe, BSI standard BS-7786: 2006 standard specifies the quality of various grades and PTFE thread seal tape.