New CRP pipe fittings apply DuPont Teflon PFA on a larger scale
25 June 2012
UK based Corrosion Resistant Products (CRP) has started commercial production of large diameter pipe fittings (up to 14 inches) for the chemical processing industry that are lined with DuPont Teflon PFA fluoropolymer resin. These new larger-sized fittings include a 90-degree elbow that is claimed to be unique in terms of its use of PFA for lining purposes.
CRP uses Teflon PFA as it provides the highest resistance to permeation of all of the fluoropolymers and is the material of choice for the most aggressive conditions. Responding to market requirements, CRP has worked to increase the size range of Teflon PFA lined pipe-fittings from 6in (DN150) to 14in (DN350) – a four-fold increase in product scale.
“It is no small achievement to create the ability to transfer mould 25 kilogrammes of PFA, to get it to where it needs to be and then cool it, all with the lowest melt flow rate PFA,” explains Michael Bruemmer, sales and marketing director at CRP. “We have found Teflon PFA 350T-J to be the most reliable consistent material for this process, having great thermal stability, resistance to stress cracking and a generally very forgiving character in use. Moreover, with a translucent polymer the results look great and speak for themselves.”
One of the most challenging parts in the new range from CRP is the 90 degree elbow. In order to manufacture this, CRP has extended its range of investment cast steel castings, creating a one-piece (as opposed to a more usual three-piece) design. This has the advantages of matching the ASME B16.5 dimensions favoured by industry and providing precise geometry for plant build.
PFA also facilitates installation, not only with regard to its one-piece design, but also because PFA moulded flanges do not exhibit the classical memory effect, enabling fittings be taken out of line without worrying about flare faces lifting. Moreover, the superior creep performance of Teflon PFA means that flanges require much less re-tightening to achieve a seal in process. The fittings can withstand the full pressure requirement of ASME B16.5 group 1.1 materials of 14bar at a maximum temperature of 200°C.
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