Frequently Asked Questions

Q: What does Low VOC mean?

A: VOC stands for Volatile Organic Compounds which are emissions from materials. Low VOC products contribute to cleaner air. The requirements for "Low VOC" have been established by SCAQMD Rule 1168/316A (see below).

Q: Who sets the requirements for Weld-On® Low VOC solvent cements and primers?

A: The South Coast Air Quality Management District ("SCAQMD"), an air pollution control agency for southern California, sets strict emissions control requirements (Rule 1168/316A) which Weld-On meets with its Low VOC products. Many other states have adopted or are in the process of adopting SCAQMD Rule 1168/316A emission limits and/or similar limits for solvent cements and primers.

Q: Am I required to use Low VOC solvent cements and primers?
Which states require the use of Low VOC solvent cements and primers?

A: Low VOC solvent cements and primers are currently required in California, Maryland, New Jersey and Connecticut. Requirements are also under consideration in several other states, including New York, Rhode Island, and Maine. Even where not required, Low VOC products are a good idea because they contribute to cleaner air and a healthier environment.

Q: How long has Weld-On® been making Low VOC solvent cements and primers?

A: IPS® Corporation, under the Weld-On® brand name, was the first to offer Low VOC products to the plastic piping industry in 1992. Weld-On's Low VOC products have been sold into the California market, as well as almost all other states and internationally, for over 15 years and have a proven track record as the best cements on the market.

Q: How are Low VOC solvent cements and primers different than non-Low VOC solvent cements and primers?

A: Weld-On's Low VOC solvent cements and primers provide the same performance, have the same installation properties, but are better for the environment and more user-friendly than non-Low VOC products.

Q: Will CPVC solvent cement work on a PVC piping installation?

A: Yes. CPVC solvent cement technically will work on PVC piping. However, we recommend that the correct Weld-On primer and PVC solvent cement for the particular application should be used. Please note that PVC solvent cement, because of temperature limitations, is not recommended for CPVC piping.

Q: Should the primer be dry before the solvent cement is applied?

A: No. The Weld-On primer must be wet and fluid. The purpose of the primer is to soften the joining surfaces of the pipe and fitting allowing proper penetration and dissolution of joining surfaces prior to Weld-On solvent cement application. This step is specifically recommended for large diameters, PVC Schedule 80, CPVC piping and cold weather installations.

Q: Why can gray CPVC solvent cement NOT be used on riser piping for a hot and cold potable water application?

A: According to IPC and UPC (International and Uniform Plumbing Codes), a purple primer and orange CPVC solvent cement must be used on all CPVC potable water applications using gray CPVC IPS (Iron Pipe Size) riser piping.

Q: Will the dauber, inside a quart can, work on 8-inch diameter pipe and fittings?

A: No. For 4-inch and larger diameter piping, we recommend the use of 4-inch swab to apply our primers and solvent cements. A can dauber is appropriate for use on pipe diameters that are approximately twice the size of the dauber diameter.

Q: How much time should be allowed before a 6-inch diameter CPVC piping system installed at 85°F (29°C) be hydrostatically pressure tested?

A: The appropriate cure time for the stated application is a minimum of 24 hours after the last joint of the piping system is assembled before the system can be hydrostatically pressure tested. Please refer to the set and cure time charts for our Weld-On products. Set Time is the time required before the joint can be carefully handled. Cure Time is the time required before the piping system can be hydrostatically pressure tested at a maximum of 150% of the system design pressure.
DANGER: Air or compressed gas must NEVER be used for system acceptance testing. Use HYDROSTATIC (water) PRESSURE TEST ONLY. System failure, when using compressed air or gas for system acceptance testing, can result in bodily injury, death, and/or property damage.

Q: Is the application of primer necessary on irrigation piping system?

A: No. However, we recommend the use of primer on all PVC piping systems. Some Weld-On PVC solvent cements for irrigation piping can be used without primer on non-pressure systems if local codes permit.

Q: Why do failures occur with PIP piping where the splits are located on the bottom of the pipe behind the joint?

A: Such failures are caused by puddling of the primer and/or solvent cement inside the joint at its lowest point. The puddling is due to an excessive application or running of primer and/or solvent cement inside the fitting or beyond the bell-end of the pipe.

Q: Since there are so many primers and solvent cements available, how should I select the correct products for my job?

A: Identify the parameters of the particular application:

  • Pipe material – PVC, CPVC, ABS
  • Schedule or SDR of piping – Sch.40, Sch.80, SDR21, etc.
  • Pipe diameter
  • Working pressure of piping system
  • Ambient temperature at the time of installation
  • Temperature of media conveyance within the piping system
  • Type of media being conveyed within the piping system – water, specific chemicals, etc.
  • Other variables which may affect application and/or piping syste

Consult the Weld-On Selection Guide and Product Guide for more information or contact your local Weld-On sales representatives for recommendation. Please call 1-800-888-8312 for your nearest Weld-On sales representative office. If further technical assistance is required, contact our Technical Service Hotline at 1-877-477-8327.

Q: Is there chemical resistant solvent cement available?

A: Weld-On 724 CPVC solvent cement is the best chemical resistant solvent cement available in the marketplace. It is specifically formulated for use in BOTH PVC and CPVC piping systems for chemical, industrial and waste water applications. This cement must be used with Weld-On P-70 primer. For a more detailed explanation and chemical test results, please refer to our brochure, product bulletin, and MSDS.

Contact our Technical Service Hotline at 1-877-477-8327 for additional assistance and/or inquiry about free on-site solvent weld training seminar.

Q: Is it necessary to hot-air back-weld a solvent-welded joint?

A: No, because hot air back welding adds no additional strength to the joint. In addition, hot air back welding immediately following the assembly of a solvent-welded joint may actually hinder the necessary curing of the joint and affect the integrity of the chemical bond itself. This is a costly additional step to the joining procedure for which there is no technical or functional benefit.

Q: What is the shelf life of primers and solvent cements?

A: Weld-On primers, PVC and ABS solvent cements: 3 years shelf life
Weld-On CPVC solvent cements: 2 years shelf life

All Weld-On primers and solvent cements have expiration dates imprinted on the outside of the case boxes and the manufactured date imprinted on the bottom of each can. The shelf life is also stated in the product bulletin of each Weld-On product.

Q: How is a Class I solvent welded pipe joint made?

A: A solvent welded pipe joint is made in accordance with ASTM D 2855 Standard Practice for Making Solvent-Cemented Joints with Poly(Vinyl Chloride) Pipe and Fittings. See our Weld-On Best Practices for Solvent Welding Thermoplastic Piping: PVC, CPVC, and ABS for more details including features on ASTM D 2855 standards.

Please also refer to Weld-On product bulletins, installation guide, and installation DVD. Or contact our Technical Service Hotline at 1-877-477-8327 for inquiry about free on-site solvent welding and ASME B31.3 bonder qualification seminar.

Q: Where can I obtain information about Weld-On products?

A: Please refer to Product Literature and/or browse through our website for more product details.

Back to top