Joining Techniques

Harvel LXT piping products are easily joined by the solvent-cementing process. Unlike conventional PVC solvent-cementing techniques, this product utilizes a one-step solvent-cement system specifically formulated for “clean” applications. This solvent cement exhibits extremely fast set and cure times. When properly used, this system results in very short cure times prior to pressure testing, and produces a solvent-cemented assembly with an exceptionally low percentage of chemical additives, reducing the potential for system contamination.

A thorough understanding of the solvent cement joining process and proper assembly techniques must be used during assembly of these products to ensure the highest system integrity. Installers must become familiar with this process prior to use.

Basic Principles of Solvent Cementing

Harvel LXT components are manufactured to the dimensional tolerances for Schedule 80 pipe per ASTM D1785, and Schedule 80 socket-type fittings per ASTM D2467. When fittings are produced to these dimensions, the ID of the fitting at the entrance of the socket is larger than the ID of the fitting at the socket bottom. The taper created by fitting socket dimensions provides an interference fit during assembly of the components. This provides a proven means for proper mating of components, ensuring adequate joint strength when properly assembled.

The following points must be clearly understood to ensure satisfactory joints are obtained consistently.

  1. The joining surfaces must be softened and made semifluid.
  2. Sufficient cement must be applied to fill the gap between the pipe and fitting.
  3. Assembly of pipe and fitting must be made immediately while the surfaces are still wet and the cement is fluid.
  4. Joint strength develops quickly as the cement dries. In the tight part of the joint, the surfaces will tend to fuse together; in the loose part of the joint the cement will bond to both surfaces.
Softening and Penetration
These areas must be softened and penetrated. (This can be achieved by the cement itself.)
These areas must be softened and penetrated.
Sufficient Application of Cement
More than sufficient cement to fill the gap in the loose part of the joint must be applied. In addition to filling the gap, adequate cement layers will penetrate the joining surfaces and remain fluid until the joint is assembled.
Cement coatings of sufficient thickness.

Joint Integrity

When the cement coating on the pipe and fittings are fluid during assembly, they will tend to flow together and become one cement layer. In addition, the surfaces beneath the cement coating will be soft from surface penetration of the cement. The softened surface areas in the tight part of the joint will tend to fuse together. As the solvent dissipates, the cement layer and the softened surfaces will harden with a corresponding increase in joint strength. The dissipation of the solvent from Harvel LXT One-Step Cement occurs very quickly due to its high evaporation rate. Joint strength develops more quickly in the tight (fused) part of the joint than in the looser (bonded) part of the joint. A properly assembled joint will take the required working pressure before the joint is fully dry and final joint strength is obtained.

 

Bonded Surfaces Fused Surfaces Surfaces must be assembled while they are wet and soft.

 

Harvel LXT® One-Step Cement

Use only Harvel LXT One-Step Cement formulated for Harvel LXT applications using the appropriate size applicator. Carefully read and follow the label on the cement can, and application and cure time instructions thoroughly. NOTE: Dauber is supplied in pint-can lid (suitable for pipe sizes 1⁄2"–11⁄4"). Dauber is supplied in quart-can lid (suitable for pipe sizes 11⁄2"–3"). For pipe sizes 4" through 6", use a roller equal in size to half the pipe diameter.

Harvel LXT One-Step Cement is listed by NSF International and conforms to the requirements of ASTM D2564.