NONMETALLIC PIPING / LINED PIPING

NONMETALLIC / LINED PIPING

 

NONMETALLIC PIPING

• Used where the problem of corrosion is severe and it is difficult to get
a suitable metallic piping.
• Useful for handling corrosive or hazardous gases and dilute mineral
acids.
• Plastics are employed in three ways:
1. Plastic pipe.
2. Filled plastic materials (glass-fiber-reinforced, carbon filled etc.)
3. Lining or coating material.
• Temperature limitations restrict the use of these non-metallic piping.
• The commonly used materials are
1. PTFE
2. FRP
3. FRV
4. PVC : Polyvinyl chloride.
5. Polypropylene,
6. GDPE,
7. LDPG,
8. ABS : Acrylonitrile-butadiene-styrene
9. CAB : Cellulose-acetate-butyrate.
10. Polyolefins.
11. Polyesters,
12. Cement,
13. Ceramic etc.

PLASTIC PIPING

• Many plastics are not lanneable.
• Ultraviolet and other forms of energy can break the bond,
• Two Categories : Thermoplastic and Thermoset.
• Properties can be modified with addition of fibres, fillers, ultraviolet
stabilizers, coloured pigments and flame retardants.
• Most cost effective – unmatched in corrosion.
• High strength to weight ratio.
• Good thermal insulation.

GLASS

• All glass piping is used for chemical resistance, cleanliness and
transparency.
• Glass pipe is not subject to ‘crazing’ often found in glass-lined pipe and
vessels subject to repeated thermal stresses.
• Pipes, fittings and hardware are available both for process piping and
for drainage.
• ‘Corning Glass Works’ offers a Pyres ‘Conical’ system for process
lines in 1”, 11/2”, 2”, 3”, 4”, and 6” sizes (ID) with 450 F as the

maximum operating temperature and pressure ranges 0-65 PSIA (1”-
3”), 0-50 PSIA (4”) and 0-35 PSIA (6”).
• Glass cocks, strainers and thermowells are available.
• Pipe fittings and equipments are joined by flange assemblies which
bear on the thickened conical ends of pipe lengths and fittings.
• Corning also offers a Pyrex Acid-Waste Drainline system in 11/2”, 2”,
3”, 4”, and 6” sizes (ID) with breaded ends joined by Teflon-gasketed
nylon compression couplings.
• Both corning systems are made from the same borosilicate glass.

LINED PIPING

• To add mechanical strength with the corrosion properties of nonmetallic
materials, the concept of lining of material is established.
• Lengths of lined pipe and fittings are joined by flanges, and elbows,
tees etc are available flanged.
• Linings (rubber for example) can be applied after fabricating the piping
but pipe is often prelined and manufacturers give instructions for
making joints.
• Carbon-steel pipe zinc-coated by immersion into molten zinc (hot-dip
galvanized) is used for conveying drinking water, instrument air and
various other fluids.
• Rubber lining is often used to handle abrasive fluids.
• The combination normally used in the industry are:
1. Mild steel rubber lined (MSRL)
2. Mild steel glass lined (MSGL).
3. Mild steel Cement Lined.
4. Mild steel PP lined.
5. FRP with PP lined.
6. Mild steel PTFE lined.
• The requisition of lined pipes has to be studied case by case based on
the service conditions.

• These specifications are under the jurisdiction of ASTM committee F-17
on plastic piping systems.
• The standards are subject to revision at any time by responsible
technical committee and are reviewed every five years and if not
revised, either re-approved or withdrawn.

ASTM SPECIFICATION PERTAINING TO METAL PIPING LINED WITH PTFE, FEP, PVDF, PP