Loctite 5331 Plastic Pipe Thread Sealant 100ml

Loctite 5331 (Henkel SI 5331) is a one-component, white, low strength silicone paste for sealing the threads of plastic pipe fittings carrying hot or cold water. It is an acetoxy silicone that cures with atmospheric humidity.

It gives an instant seal against 0.05 MPa water pressure on 25.4 mm fittings, and full sealing to 0.3 MPa within 12 hours when the atmospheric humidity is at least 40 %.

Where this product is used

• Thread sealing of plastic pipe threaded fittings carrying hot water
• Thread sealing of plastic pipe threaded fittings carrying cold water
• Steel fittings carrying water/glycol (tested through 20 to 90 °C cycling for 12 months without leaking)
• Hot water lines where the seal holds 0.3 MPa in water at 90 °C

Features

• One component, no mixing
• White paste; silicone, acetoxy type
• Cure speed independent of the substrate
• Instant seal against 0.05 MPa water pressure on 25.4 mm fittings
• Full sealing to 0.3 MPa within 12 hours at 40 % relative humidity or above
• Low strength maintained up to 150 °C
• Seal holds 0.3 MPa in water at 90 °C

Key specifications

Selecting the right option

Loctite 5331 is a low strength silicone sealant for plastic pipe threads. For other thread sealants in the range see Loctite 577 Medium Strength Thread Sealant and Loctite 567 PST Low Strength Thread Sealant.

Check the data sheet and the safety data sheet of any sealant against the pipe material and the fluid before use.

Using it

For potable water systems, allow 96 hours at 20 to 23 °C before use.

Open time is 5 minutes at 25 °C. Cure speed is independent of the substrate, but full sealing needs atmospheric humidity of at least 40 %. Low temperatures do not reduce effectiveness unless the atmospheric moisture is also low.

Storage and handling

Store unopened in a dry location, optimally between 8 °C and 21 °C. Storage below 8 °C or above 28 °C can adversely affect the properties of the product.

Limits and safety

Not recommended for pure oxygen or oxygen-rich systems, or as a sealant for chlorine or other strong oxidisers. Read the safety data sheet before use.

Frequently asked questions

What is Loctite 5331 used for?

Thread sealing of plastic pipe threaded fittings carrying hot or cold water.

How fast does Loctite 5331 seal?

It gives an instant seal against 0.05 MPa water pressure on 25.4 mm fittings, and full sealing to 0.3 MPa within 12 hours at 40 % relative humidity or above.

How long should Loctite 5331 cure before potable water use?

Allow 96 hours at 20 to 23 °C.

Does Loctite 5331 have WRAS, DVGW or NSF approvals?

The Henkel data sheet lists NSF Category P1 registration, for sealing where there is no possibility of food contact, and calls it a regional approval. Henkel's product page also lists DVGW, NSF and WRAS approvals, which are not in the data sheet. Contact AIMS if you need a certificate for a specific application.

How hot can a joint sealed with Loctite 5331 get?

The data sheet states low strength is maintained up to 150 °C, and the seal holds 0.3 MPa in water at 90 °C. It states no separate operating range.

Related products

See also: Loctite 577 Medium Strength Thread Sealant, Loctite 567 PST Low Strength Thread Sealant, Loctite 565 PST Thread Sealant 50ml, Loctite 542 Medium Strength Thread Sealant, Loctite 569 Low Strength Thread Sealant 50ml.