To obtain maximum performance from FLUOROPOLYMER lined piping, it is important that the flared end joints be protected from damage during storage handling and installation. The protective end caps on the lined items should be in place, until the items are ready for installation. When removing the protectors, do not rotate the flanges, and damage the PTFE sealing faces. To protect liners, avoid rough handling, especially when temperatures are below 40°F (4°C).
Practical precautions to be observed with these products are:
- a) No welding operations should be done on the lined items or other components, since excessive heat can cause liner decomposition and failure.
- b) No part of the metal sheath of the lined system should be used as an electrical earthing. If grounding for static electricity is necessary, kindly consult us.
The same general techniques used to install flanged carbon steel piping systems can be applied to FLUOROPOLYMER Lined piping.
When assembling, always use a full complement of clean, new machine bolts. Apply bolt lubricant to the full length of the bolt threads. Table -1 lists minimum recommended bolt torques for each liner type and pipe size.
Care should be taken when tightening over-torquing, as it can cause damage to the PTFE sealing surfaces.
Tighten the flange bolts with a torque wrench; use a criss-cross pattern that alternately tightens the bolts located 180° apart.
TABLE - 1
In order to avoid problems to sealing surfaces by over or under tightening of bolts, the following torque values should be used: -
Torques To Be Followed During Installation
(Torque values are for bolts with lubricated threads)
|NB||ASA 150||ASA 300||PN 10|
|No. Of Bolts||of Bolts||Torque mm.||No. of Bolts||of Bolts||Torque mm.||No. of Bolts||of Bolts||Torque mm.|
|20||4||M 12||4||4||M 16||5||4||M 12||10|
|25||4||M 12||5||4||M 16||5||4||M 12||20|
|32||4||M 12||10||4||M 16||10||4||M 16||30|
|40||4||M 16||10||4||M 20||15||4||M 16||40|
|50||4||M 16||20||8||M 16||10||4||M 16||50|
|65||4||M 16||30||8||M 20||15||4||M 16||70|
|80||4||M 16||40||8||M 20||20||8||M 16||40|
|100||8||M 16||30||8||M 20||30||8||M 16||40|
|125||8||M 20||40||8||M 20||40||8||M 16||50|
|150||8||M 20||50||12||M 20||35||8||M 20||60|
|200||8||M 20||70||12||M 22||55||8||M 20||90|
|250||12||M 22||70||16||M 24||55||12||M 20||60|
|300||12||M 22||90||16||M 27||85||12||M 20||70|
|350||12||M 24||110||20||M 27||74||16||M 20||110|
|400||16||M 24||110||20||M 30||100||16||M 24||160|
|500||20||M 27||140||24||M 30||130||20||M 24||180|
|600||20||M 30||200||24||M 36||195||20||M 27||240|
After the operating temperature has been reached the flange joints should once again be tightened according to the given torque. If there is any leak, the flange connection should be checked for squareness of flanges and for continuation or damage on the sealing surfaces. Slight damage can be removed by emery paper.
Sandblasting and painting should be done with care to protect the raised PTFE face. Make sure that the protective caps are in place at all times, during these operations, and direct sandblasting away from the flange face.
If the exterior of the pipe is to be treated with a heat curable protective coating, exercise caution during the heating process. Never apply heat in excess of the mentioned limit.
Vent holes in items should not be plugged with paint. Vent holes are a part of the venting system and are needed to avoid any possible gas build up between the liner and the metalcasing.
Hanger spacing for FLUOROPOLYMER Lined piping is essentially the same as recommended for schedule 40 carbon steel piping. It is recommended that each spool be supported near the flange connection for maximum protection against excessive deflection. Additional support is recommended where piping changes direction, and in areas of high load concentrations, such as clusters of valves or fittings. The type of supports or hangers used should permit freedom of movement resulting from temperature changes.
THERMAL EXPANSION ALLOWANCE
The thermal expansion for FLUOROPOLYMER Lined piping can be considered the same as that for carbon steel piping. Thermal expansion can be compensated by using expansion joints or expansion loops.
Gaskets are not required between PTFE flared faces except when they are connected to a flange face of another material such as metal, glass, carbon, ceramic, rein forced PTFE etc.
DO NOT ROTATE SCREWED FLANGES
If a problem of bolt hole alignment develops, loosen bolts on as many upstream and downstream connections as necessary to obtain the required alignment, and then retighten all connections, (Lap joint flanges should be employed in locations where this is impractical). Hairline cracks in tack welds of screwed flanges are of no consequences since; these welds have no sealing or structural purpose, but simply lock the threads even when cracked.
Do not remove bolts nor remove sections while the system is above 65°C as sealing faces may distort and cause sealing difficulties on reinstallation. Flange covers or blind flanges should be immediately installed on any sections, which are removed from the system to secure the sealing faces and protect them from damage when not in use.
Always store PTFE Lined Pipes and Fittings, in properly stacked conditions with flange face covers in position. Do not store unused Pipes/ Fittings in corrosive atmosphere or on site, in corrosive plants.
Store in well-ventilated warehouses away from all sources of flame and heat over 40°C, and acids in acidic process plants.
ERECTION OF BELLOWS
While installing PTFE Bellows, limiting bolts must not be removed or tampered with, as they are adjusted at the factory for maximum permissible extension as permissible.
Both the adjacent components of the PTFE Bellows should be supported securely to avoid any unwanted stress in the PTFE body of the bellows.