Project requirements · Chemical
Lead sheath (hydrocarbon and chemical barrier)
An extruded lead sheath keeps aromatic hydrocarbons and chemicals out of the insulation in contaminated ground.
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Constructions that meet it
- Lead sheath under the outer sheath: changes the cable's layers. Extruded lead (alloy) sheath over the inner covering, then bedding, armour and outer sheath (Pb). Drawbacks: Very heavy; lead is a restricted substance in some markets; fatigue under vibration; must be earthed.
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Tests
No international test method: specifications state this in words. Tests that exist:
- IEC 60502-1 / -2 (metallic sheath of lead): construction requirement (thickness by the standard); no hydrocarbon test. Pass: thickness
How specifications state it
Specified by construction ('lead sheathed', 'Pb'), not by a test.
Where it is asked for
- refineries and petrochemical plants
- tank farms
- contaminated soil
Sources
- Helukabel HELUPOWER 1000 HY-CARBO LEAD GSTA datasheet 1DB_17002500 (XLPE, PVC inner sheath, lead cover, double galvanised steel tape armour, hydrocarbon resistant PVC outer sheath) (maker's catalogue)
- EN 50288-7:2005 (BS EN 50288-7, owner's copy), 4.18 and 4.18.1, p. 11 to 12: chemical or environmental protection of instrumentation and control cables by a lead sheath to EN 50307, nominal thickness LRt = 0,03 D + 0,7 mm (at least 0,8 mm), D the diameter under it (Table C.1); at any point at least 0,95 LRt - 0,1 mm; or a multi-layer sheath (Al foil at least 0,15 mm, HDPE at least 1,0 mm, polyamide at least 0,3 mm) (read in the standard)
- Nexans / Lynxeo EN 50288-7 XLPE OS Armoured LC (lead sheath for aromatic hydrocarbons) (quoted by others)
- Kabelwerk Eupen, Materials for specific requirements, p.2 (lead sheath with PE outer sheath) (maker's catalogue)