Tubing Pressure Specifications
Fluorotherm® tubing is specified and used in many applications that require a combination of high temperatures and working pressures, including live steam at up 100 psig. For specific applications that need to operate in the high ranges of these parameters, we conduct specific tests to certify estimated pressure rating, if required.
Many of our products, especially high pressure heat exchangers, utilize Fluorotherm ® tubing to convey high pressure fluids in a broad range of temperatures. Fluid types include, steam, hot oil, water, water/glycol mix and air and gases.
You can roughly estimate the pressure rating of any tubing, including Fluorotherm ® tubing, by the well-established Barlow’s hoop strength formula:
2 x Tensile Strength x Wall Thickness / OD
Another formula for burst pressure is the following:
Tensile Strength x 0.25 x (OD^2-ID^2) / ID^2 x 0.25 x (1+OD^2/ID^2)
The tensile strengths of unfilled fluoropolymers, at ambient temperatures, is usually represented as follows:
PTFE – 2500 psi (17.2 MPa)
FEP – 3400 psi (23.4 MPa)
PFA – 4000 psi (27.6 MPa)
ETFE – 6960 psi (48.0 MPa)
ECTFE – 6960 psi (48 MPa)
PCTFE – 6060 psi (41.8 MPa)
PVDF – 7830 psi (54.0 MPa)
PEEK – 13000 psi (89.6 MPa)
Fluorotherm™ Polymers Inc., utilizes specialized, internally developed formulas to evaluate burst pressures variation with temperatures, and, if required, can simulate tests to establish the burst and safe working pressures. Fluorotherm™’s technical staff is available for assistance in materials selection.
Note: The above formulas only apply to an ambient temperature of 25 C or 77 F.
Note: ID is the inside diameter, OD is outside diameter
Note: At elevated temperatures, the burst pressure drops precipitously. Be careful to take this into consideration, as PTFE, FEP and PFA hold ambient pressure rating with a higher stability than the other materials listed. The thermal stability and upper use temperatures of the materials are key considerations where temperatures higher than ambient are in effect.