Tetrachloroethylene (PCE) Storage & Tank Compatibility

Storing Tetrachloroethylene (PCE)? Start Here

Tetrachloroethylene (PCE, also called perchloroethylene or "perc," CAS 127-18-4, C₂Cl₄) is a colorless, dense chlorinated solvent best known from dry cleaning, metal vapor degreasing, and as a chemical intermediate. It is noncombustible (NFPA flammability rating 0, no flash point), but it is far from benign: it is denser than water (1.63), essentially insoluble, and a strong solvent that attacks plastics and many elastomers.

Because PCE is a chlorinated solvent, it readily permeates and swells polyethylene and polypropylene — the materials most plastic tanks are built from. For that reason, PCE storage and recovery is a job for properly specified metal tanks (stainless or carbon steel) with PTFE sealing, not for poly tanks. PCE is also classified by IARC as Group 2A (probably carcinogenic to humans) and the U.S. DHHS lists it as reasonably anticipated to be a human carcinogen, with well-documented central nervous system (CNS) depressant effects, so closed, vapor-tight, recovery-oriented systems are the norm.

Why Polyethylene Tanks Are Not Suitable for PCE

Polyethylene (HDPE and crosslinked XLPE) tanks are the workhorses of water, brine, and many aqueous chemical applications — but they are the wrong choice for tetrachloroethylene. PCE is a nonpolar chlorinated solvent that is absorbed into the polyethylene matrix, where it permeates the wall and causes the plastic to swell, soften, and lose mechanical strength and environmental stress-crack resistance. The same failure mode applies to polypropylene and to PVC/CPVC.

The result is permeation loss of product, vapor escape (a serious concern given PCE's carcinogen classification), and eventual loss of containment. There is no poly grade we recommend for PCE service. For storage, day tanks, and solvent recovery, the correct path is metal construction — carbon steel for many degreasing systems and 304/316 stainless steel for purity-critical or long-term storage — with the solvent kept dry to avoid hydrolysis to hydrochloric acid. If you are currently holding PCE or a PCE-bearing waste stream in a poly tank, treat it as a containment risk and contact us to scope a proper steel or stainless solution.

Specify the right vessel for PCE: Our solvent recovery systems, certified carbon steel tanks, and custom 304/316 stainless tanks are built for aggressive chlorinated solvents. Talk to our fabrication engineers at 866-418-1777 to scope a dry-stored, vapor-tight, recovery-ready solution.

Material compatibility at a glance

PCE is an aggressive chlorinated solvent. The correct materials of construction are metal: 304/316 stainless steel (preferred) or carbon steel, both stored dry to prevent hydrolysis to HCl. Use PTFE gaskets and seals; avoid most rubbers and avoid aluminum. Polyethylene, polypropylene, and PVC/CPVC are NOT suitable — PCE permeates and swells these plastics.

Ratings: S suitable · C conditional / limited · U unsuitable. Verify against the cited resistance charts and your concentration/temperature before specifying.

The safety that actually matters

Carcinogen and CNS hazard. PCE is classified by IARC as Group 2A (probably carcinogenic to humans) and is listed by the U.S. DHHS as reasonably anticipated to be a human carcinogen. It is a central nervous system depressant: exposure can cause dizziness, headache, drowsiness, impaired coordination, and at high concentrations loss of consciousness. Repeated exposure is associated with organ (liver, kidney) and neurological effects. Engineer for closed, vapor-tight handling with effective ventilation and follow current OSHA/NIOSH exposure limits.

Thermal/UV decomposition. On heating or exposure to UV light, PCE decomposes to phosgene and hydrogen chloride — both highly toxic. Keep PCE away from open flames, hot surfaces, welding arcs, and strong light. Although noncombustible, contact with hot metal or fire still generates these toxic gases.

Hydrolysis — keep it dry. PCE slowly reacts with water to form trichloroacetic acid and hydrochloric acid. In steel systems this drives corrosion, so PCE should be kept dry and stored in clean, moisture-excluded vessels; stabilized/inhibited grades and 316 stainless add margin where trace moisture cannot be fully avoided.

Reactive metals. PCE reacts with finely divided light metals; the reaction with aluminum and zinc can be violent, and mixtures with finely divided barium or lithium can be explosive. Avoid aluminum tankage and aluminum fittings in PCE service.

Environment. PCE is a dense, persistent groundwater contaminant (it sinks as a DNAPL) and is toxic to aquatic life. Provide secondary containment and prevent any release to soil or water.

Common questions

Can I store tetrachloroethylene (PCE) in a poly (polyethylene) tank?

No. PCE is a chlorinated solvent that permeates and swells polyethylene, polypropylene, and PVC/CPVC, degrading the wall and causing loss of containment. PCE requires metal construction — 304/316 stainless steel or carbon steel.

What is the best material of construction for PCE storage?

304 or 316 stainless steel is preferred for purity-critical and long-term storage; carbon steel is widely used in degreasing and recovery systems. In all cases the solvent must be kept dry to prevent hydrolysis to hydrochloric acid. Use PTFE gaskets and seals, and avoid aluminum and most rubbers.

Is PCE flammable?

No. PCE is noncombustible with an NFPA flammability rating of 0 and no flash point. However, it is not inert: on heating or UV exposure it decomposes to toxic phosgene and hydrogen chloride, so keep it away from flames, hot surfaces, and welding.

Why does PCE need to be stored dry in steel tanks?

PCE slowly hydrolyzes in the presence of water to form trichloroacetic acid and hydrochloric acid. That acid attacks carbon steel and can affect stainless. Keeping the solvent dry, using stabilized grades, and selecting 316 stainless where moisture is a risk all protect the vessel.

Is PCE a carcinogen?

Yes. IARC classifies PCE as Group 2A (probably carcinogenic to humans) and the U.S. DHHS lists it as reasonably anticipated to be a human carcinogen. It is also a CNS depressant. Handle it in closed, vapor-tight, recovery-oriented systems with proper ventilation.