Smith-Blair Joint Restraint

Smith-Blair joint restraint systems prevent pipe pull-out at mechanical joints, couplings, and fittings under pressure — the single most common cause of catastrophic pipeline failure in water distribution systems. Every change in pipe direction, diameter, or termination generates a thrust force proportional to operating pressure and pipe cross-sectional area. Without restraint, that force will eventually work a joint loose.

Smith-Blair's joint restraint product line covers four distinct restraint mechanisms: CamLock cam-action bite rings, serrated wedge action restraint, tie rod through-bolt systems, and integral coupling restraint. Each system is engineered for specific pipe materials, joint types, and pressure classes — the wrong restraint for the application can fail without warning.

As an authorized Smith-Blair distributor, Watermain Supply stocks and sources the complete restraint catalog. Contact us with your pipe material, OD, joint type, and operating pressure for product selection and project pricing.

Tie Rod & Nut Sets — Style 101 (Alloy Steel)

Style 101 tie rod and nut sets provide a traditional through-bolt restraint system that spans across mechanical joint couplings, connecting the follower rings on each side of the joint to prevent axial separation. This is the simplest and most universally compatible restraint method — no special coupling modification required. Alloy steel construction provides the tensile strength required for large-diameter, high-pressure applications.

Used on pump station piping, valve installations, and any mechanical joint connection that cannot be concrete-blocked or where the engineer specifies full rod restraint. Specify pipe size and number of rods required per connection.

Serrated Joint Restraints — Style 101 Series

Smith-Blair serrated joint restraints use hardened serrated wedge segments that dig into the pipe OD as the joint is pressurized — the higher the internal pressure, the greater the grip force. This self-energizing behavior makes serrated restraints particularly effective on high-pressure systems where pressure surges can generate thrust peaks well above the normal working pressure.

Available in three pipe and joint configurations — ensuring correct bite geometry for each pipe material's hardness and surface characteristics:

• Style 101 – Serrated Joint Restraint, MJ Fittings — for ductile iron mechanical joint fittings; compatible with AWWA C110/C153 MJ dimensions
• Style 101 – Serrated Joint Restraint, AWWA DI PVC Pipe — for PVC pipe in ductile-iron OD sizes (C-900 DR14, DR18, DR25); hardened segments calibrated for PVC hardness
• Style 101 – Serrated Joint Restraint, Bell & Spigot PVC Joints — for bell-and-spigot PVC pipe joints; segments engage the spigot OD to prevent pull-out from the bell

CamLock Joint Restraints — Style 111

Smith-Blair Style 111 CamLock is the premium joint restraint system for mechanical joint fittings and couplings. The patented CamLock cam-action design engages the pipe OD with a rotating cam segment that locks into position as the gland bolt is tightened — creating a mechanical interlock that cannot back off under pressure cycling, surge, or soil movement. CamLock restraints meet or exceed AWWA restraint performance requirements and are the system of choice for new DI water main installations across the US.

• Style 111 – CamLock Joint Restraint — standard configuration; for DI and cast iron pipe
• Style 111 – CamLock Joint Restraint, PVC Pipe — cam geometry and bite force calibrated specifically for PVC pipe wall hardness and deflection properties
• Style 111 – CamLock Joint Restraint, PVC Pipe, MultiSeal — MultiSeal configuration provides a secondary gasket seal at the gland in addition to the cam restraint; for wet or below-water-table installations
• Style 111 – CamLock Joint Restraint, Steel Pipe — for carbon steel pipe mechanical joint connections in industrial and transmission applications
• Style 111 – CamLock Joint Restraint, MultiSeal, MJ Gaskets — dual-seal configuration for MJ gasket joints; adds a redundant seal at the restraint ring
• Style 111 – CamLock Joint Restraint, MultiSeal — general MultiSeal variant for ductile iron pipe with enhanced sealing requirements
• Style 111 – CamLock Joint Restraint, Cast & Ductile Iron Pipe — dual-material specification covering both cast iron legacy systems and new ductile iron mains

CamLock Joint Restraints — Style 120

Style 120 is the expanded-diameter CamLock variant for large-diameter pipe and applications requiring a wider gland ring. It carries the same cam-action restraint mechanism as Style 111 but is engineered for the larger bolt-circle and gland dimensions of 14" and larger mechanical joint fittings. Available in the same material and seal configurations:

• Style 120 – CamLock Joint Restraint, PVC Pipe, MultiSeal
• Style 120 – CamLock Joint Restraint, PVC Pipe
• Style 120 – CamLock Joint Restraint, Steel Pipe
• Style 120 – CamLock Joint Restraint, MultiSeal, MJ Gaskets

Restraint Selection: What You Need to Know

Selecting the correct joint restraint requires knowing: pipe material (DI, PVC C-900/C-905, steel, cast iron), nominal pipe size, pipe OD, joint type (MJ, bell-and-spigot, coupling), system working pressure, test pressure, and whether a MultiSeal secondary gasket is required by specification. Using a restraint designed for DI pipe on PVC, or vice versa, can result in inadequate bite force and joint failure — the products are not interchangeable.

Call: 281.664.8000  |  Email: sales@watermainsupply.com