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Smith-Blair Joint Restraint
Smith-Blair Style 471 PipeLock Restraint Coupling - Ductile, 3-36 in
Smith Blair
Smith-Blair Style 471 PipeLock Restraint Coupling - Ductile, 3-36 in
- Price
- From $447.64
Smith-Blair Style 920 FlangeLock Restrained FCA for PVC Pipe | Cam-Lock | 4"-24"
Smith Blair
Smith-Blair Style 920 FlangeLock Restrained FCA for PVC Pipe | Cam-Lock | 4"-24"
- Price
- From $585.89
Smith-Blair Style 923 FlangeLock MJ Coupling Body | Flange x MJ | Restrained | 4"-42"
Smith Blair
Smith-Blair Style 923 FlangeLock MJ Coupling Body | Flange x MJ | Restrained | 4"-42"
- Price
- From $446.33
Smith-Blair Style 472 PipeLock Restraint Coupling - PVC, 3-30 in
Smith Blair
Smith-Blair Style 472 PipeLock Restraint Coupling - PVC, 3-30 in
- Price
- From $444.71
Smith-Blair Style 911 FlangeLock Restrained FCA | Ductile Iron & Steel | Cam-Lock | 3"-36"
Smith Blair
Smith-Blair Style 911 FlangeLock Restrained FCA | Ductile Iron & Steel | Cam-Lock | 3"-36"
- Price
- From $443.34
Smith-Blair EZW Seal & Restraint Line Cap - 2-12 in
Smith Blair
Smith-Blair EZW Seal & Restraint Line Cap - 2-12 in
- Price
- From $245.55
Smith-Blair EZW Maxi-Grip Restraint Reducing Coupling - 3-12 in
Smith Blair
Smith-Blair EZW Maxi-Grip Restraint Reducing Coupling - 3-12 in
- Price
- From $513
Smith-Blair EZW Restrained Flanged Coupling Adapter - 2-12 in
Smith Blair
Smith-Blair EZW Restrained Flanged Coupling Adapter - 2-12 in
- Price
- From $425.88
Smith-Blair EZW Maxi-Grip Restraint Coupling - Straight, 2-12 in
Smith Blair
Smith-Blair EZW Maxi-Grip Restraint Coupling - Straight, 2-12 in
- Price
- From $324.31
Smith-Blair Style 907 Restraint Plate - Carbon Steel, 3-Hole, 4-48 in
Smith Blair
Smith-Blair Style 907 Restraint Plate - Carbon Steel, 3-Hole, 4-48 in
- Price
- From $87.29
Smith-Blair Style 101 Tie Rod & Nut Set - Alloy Steel, 5/8-1-1/2 in
Smith Blair
Smith-Blair Style 101 Tie Rod & Nut Set - Alloy Steel, 5/8-1-1/2 in
- Price
- From $30.80
Smith-Blair Style 473 PipeLock Restraint Steel Coupling - 3-24 in
Smith Blair
Smith-Blair Style 473 PipeLock Restraint Steel Coupling - 3-24 in
- Price
- From $428.38
Smith-Blair Joint Restraint
Authorized Smith-Blair (Xylem) Distributor
Joint Restraint
Products
3 in to 48 in
Every pressurized pipeline is trying to pull itself apart — at every bend, dead end, tee, and reducer, line pressure works to push pipe out of its joints. This is the complete Smith-Blair answer: restrained couplings engineered for ductile iron, PVC, and steel; seal-and-restraint line caps; restrained flanged coupling adapters; and the tie rods and restraint plates that harness standard couplings when the spec calls for it. No thrust blocks, no concrete cure time, no waiting.
3–48 in
Restrained Sizes
13 Products
Every Restraint Method
DI · PVC · Steel
Material-Matched Grip
Zero
Thrust Blocks Required
Education
Thrust: The Force You're Buying Protection From
Water under pressure pushes on every surface that changes its direction or its area. At 100 psi, an 8 in dead end carries thousands of pounds of axial force — permanently, plus surge. Something in the system must hold that load, and there are exactly three ways to do it.
The Three Ways to Restrain a Joint
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Thrust Blocks — Concrete Against Soil
The traditional answer: pour concrete behind the fitting and let undisturbed soil take the load. Works — until the soil is poor, the trench must close today, or someone excavates next to the block in ten years. One-directional, cure-time-limited, and only as reliable as ground you can't inspect.
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External Harness — Rods and Plates
Tie rods spanning the joint, anchored through restraint plates or flange bolt holes, carry thrust in tension around a standard coupling. Field-proven, inspectable, and the specified method on countless waterworks details — built from the Style 101 rod sets and 907 plates below.
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Integral Restraint — The Joint Grips the Pipe
Grip rings built into the coupling engage the pipe wall directly: hardened, wedge-shaped rings whose bite tightens as pressure rises. Installs in minutes, restrains both directions, immune to adjacent digging. This is where the industry has moved — and where most of this collection lives.
The engineering choice between them comes down to what the job gives you. Good soil, time to cure, one-direction thrust: blocks still work. A spec detail that draws harness rods: the 907/101 hardware builds it exactly. Everything else — PVC that can't carry thrust through its own joints, tight schedules, congested trenches, future-proof corridors — belongs to integral restraint.
Where Unrestrained Joints Fail
Dead ends and caps. First joints off bends, tees, and hydrant runs. Unanchored PVC and PE anywhere. Slopes and unstable bedding. Test headers against closed valves. If pressure can translate into axial pull at the joint and nothing is engineered to resist it, the joint will eventually move — usually during a surge, always at the worst time.
Why Grip-Ring Restraint Is Self-Energizing
The grip ring is a wedge: thrust that tries to extract the pipe drives the ring deeper into its taper, increasing the bite. Rising pressure strengthens the restraint instead of defeating it, and multi-length hardened teeth spread the load around the pipe circumference — which is how the same principle safely grips both steel and PVC.
Material-Matched Grip · PipeLock & EZW
Restrained Couplings
Gripping ductile iron, PVC, and steel are three different mechanical problems — wall hardness, allowable contact stress, and OD standards all differ. Smith-Blair solves each with a dedicated design instead of one compromise.
471
PipeLock — Ductile Iron · 3-36 in
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The large-diameter DI restraint workhorse — restrained joints on ductile mains to 36 in
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Grip geometry sized to DI wall hardness and standardized DI ODs
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Best for: tie-ins, repairs, and dead ends on ductile transmission and distribution mains
472
PipeLock — PVC x PVC · 3-30 in
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Purpose-built for plastic pipe — contact stresses tuned so the grip holds without damaging the PVC wall
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The answer to PVC's structural reality: unanchored PVC cannot carry thrust through its own joints
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Best for: C900/C905 mains — repairs, tie-ins, and every joint a thrust block used to guard
473
PipeLock — Steel & Transitions · 3-24 in
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Steel-pipe restraint plus restrained transitions across unlike outside diameters
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The fitting for restrained new-to-old connections where the ODs don't match
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Best for: steel mains and mixed-material tie-ins that must carry their own thrust
Maxi-Grip Platform · 2-12 in
EZW S & R
Seal & restraint couplings, straight and reducing
The EZW Maxi-Grip couplings stab-fit onto steel, ductile iron, PVC, or stiffened PE, with a timing gasket that seals before the grip ring engages — seal and restraint always set in the correct order. Rated by pipe: steel and DI 300 psi, PVC 235 psi, PE 200 psi. The EZWR is the only restrained reducing coupling in the line — critical, because a size change generates thrust all by itself.
- EZWS straight · 2–12 in · alloy or 304 SSView product
- EZWR reducing · 3–12 in · alloy or 304 SSView product
Newest Generation · 4-8 in
431 RazorLock
Wide-range restrained coupling — one Dual Drive bolt per end
The fastest restrained install Smith-Blair makes: stab-fit, one bolt per end driven with a standard 1/2 in square drive, 250 psi working pressure, and a size range wide enough that one coupling covers PVC, PVCO, ductile, steel, cast iron, and stiffened PE of its nominal size. Listed in our couplings collection — it belongs in both conversations.
- RazorLock 431 · 4–8 in · 250 psiView product
Ends, Gaps & Abandonments
Restraint Sleeves & Seal-and-Restraint Line Caps
Two special cases where restraint is the whole job: spanning pipe with a restrained sleeve, and closing an open end that pressure is actively trying to blow off.
Restrained Gap Spanning
477 Sleeve
PipeLock restraint steel sleeve · 3–48 in
The PipeLock grip system on a sleeve body, running all the way to 48 in — restrained joints and spans on large-diameter work where the 471/473 coupling ranges end. When the cut-out section, the misaligned ends, or the transmission-main repair also has to carry thrust, this is the fitting.
- Style 477 · 3–48 inView product
Dead Ends Done Right
EZWC Line Cap
EZW seal & restraint line cap · 2–12 in
A dead end is the purest thrust case there is — full line pressure on the cap area, all day, forever. The EZWC stabs onto the open end, seals, and restrains itself with built-in gripping members: no strapping, no blocking, no welding. Supplied with a threaded outlet and plug for pressure testing and purging. The standard answer for abandonments, phased construction ends, and test closures.
- EZWC line cap · 2–12 in · alloy or 304 SSView product
PE Pipe: Stiffeners, Always
Every restrained product on this page that accepts PE or HDPE requires a properly sized internal stiffener — the stiffener carries the radial gasket and grip loads the PE wall cannot. Unstiffened PE in any gripping coupling is a guaranteed callback. Tell us the pipe DR and we include the right stiffener on the quote.
Flange Meets Plain End · FlangeLock & EZW-F
Restrained Flanged Coupling Adapters
An FCA connects a flanged component — valve, meter, pump — directly to plain-end pipe. Add restraint and it also carries the thrust that would otherwise pull the pipe out from behind the flange: the difference between an adapter and an anchor.
911
FlangeLock Restrained FCA — DI & Steel · 3-36 in
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Flange to plain-end ductile or steel, restrained with the Cam-Lock locking system
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Valve and hydrant settings without harness rods or blocks behind the flange
920
FlangeLock Restrained FCA — PVC · 4-24 in
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The PVC-specific version — restrained flange connections on C900/C905 without stressing the pipe wall
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The critical fitting at every valve on unanchored PVC mains
923
FlangeLock MJ Coupling Body — Flange x MJ · 4-42 in
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Flange on one side, mechanical joint on the other — restrained, through 42 in
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Configured with its matching locking components — send the job details and we confirm the complete assembly
Fabricated Alternative — EZW-F · 2-12 in
The Gen II EZW restrained FCA covers 2 in to 12 in on the Maxi-Grip platform: stab-fit coupling end, AWWA C207 Class D flange standard, other flange types and special laying lengths available because the body is fabricated. 175 psi standard working pressure with higher-pressure flanges available by pipe type — the flexible-spec answer in the smaller sizes.
The Specified-Detail Method · Styles 907 & 101
Tie Rods & Restraint Plates — Harnessing Standard Couplings
Long before grip rings, waterworks details restrained sleeve couplings with external harnesses — and thousands of specifications still draw them. The method: restraint plates behind each pipe-side anchor point, tie rods spanning the coupling, thrust carried in rod tension. We stock both halves of the detail.
The Anchor Points
907 Plates
Restraint plates, carbon steel, 3-hole · 4–48 in
The lug plates that give harness rods something to pull against — three-hole carbon steel, sized 4 in through 48 in to match the pipe and the rod pattern on the detail. Sold by pipe size; the drawing's rod count and diameter determine how many plates and holes each joint needs.
- Style 907 · 3-hole carbon steel · 4–48 inView product
The Tension Members
101 Rod Sets
Tie rod & nut sets, alloy steel · 5/8 in to 1-1/2 in
Alloy steel tie rods with nuts, in the five UNC diameters harness details call out — 5/8, 3/4, 1, 1-1/4, and 1-1/2 in — across the rod lengths that span couplings and joint assemblies. Rod diameter and count come from the thrust calculation on the detail; send the drawing and we pull the exact set.
- Style 101 · 5 diameters · multiple lengthsView product
Harness or Grip Ring — Which Does the Spec Want?
If the detail draws rods and plates, build the detail — the 907/101 hardware matches it bolt for bolt, and substituting integral restraint on a harness spec is the engineer's call, not the contractor's. If the spec says "restrained joint" without a detail, integral restraint (PipeLock, EZW, RazorLock) is faster to install and inspect. Either way the thrust math is the same — only the load path changes.
The Whole Category, One Table
Restraint Product Comparison
| Style | What It Is | Pipe / Application | Sizes | Restraint Method | Reach For It When |
|---|---|---|---|---|---|
| 471 | PipeLock restrained coupling | Ductile iron | 3–36 in | Integral grip ring | Restrained DI joints and repairs to 36 in |
| 472 | PipeLock restrained coupling | PVC x PVC | 3–30 in | Integral grip ring | Every C900/C905 joint a thrust block used to guard |
| 473 | PipeLock restrained coupling | Steel & transitions | 3–24 in | Integral grip ring | Restrained joints across unlike ODs |
| 477 | PipeLock restraint sleeve | Steel · large diameter | 3–48 in | Integral grip ring | Restrained spans and joints beyond coupling ranges — to 48 in |
| EZWS | Maxi-Grip restrained coupling | Steel, DI, PVC, PE* | 2–12 in | Grip ring + timing gasket | Stab-fit restrained straight joints; alloy or 304 SS |
| EZWR | Maxi-Grip restrained reducing coupling | Steel, DI, PVC, PE* | 3–12 in | Grip ring + timing gasket | The size change that carries its own thrust |
| EZWC | Seal & restraint line cap | Dead ends · test closures | 2–12 in | Built-in gripping members | Capping the purest thrust case there is — with a test outlet |
| EZW-F | Restrained flanged coupling adapter | Flange to plain end | 2–12 in | Maxi-Grip band | Fabricated FCA — flange types and laying lengths to order |
| 911 | FlangeLock restrained FCA | DI & steel | 3–36 in | Cam-Lock system | Valve settings on metal pipe without harness rods |
| 920 | FlangeLock restrained FCA | PVC | 4–24 in | Cam-Lock system | The critical fitting at every valve on unanchored PVC |
| 923 | FlangeLock MJ coupling body | Flange x mechanical joint | 4–42 in | Cam-Lock system | Restrained flange-to-MJ connections through 42 in |
| 907 | Restraint plates, 3-hole carbon steel | Harness details | 4–48 in | External harness | Building the rod-and-plate detail the spec draws |
| 101 | Tie rod & nut sets, alloy steel | Harness details | 5/8–1-1/2 in rods | External harness | The tension members for every harnessed joint |
| 431 | RazorLock wide-range restrained coupling | PVC, DI, steel, CI, PE* | 4–8 in | Grip ring, Dual Drive bolt | Fastest restrained install — one bolt per end, 250 psi |
* PE/HDPE requires internal stiffeners on all gripping products. Restrained working pressures vary by pipe material and product — see each product page. RazorLock 431 is listed in our couplings collection and shown here for completeness.
Fast Selector
Match the Job to the Restraint
"Restrained joint on a DI main"
PipeLock 471 to 36 in; RazorLock 4–8 in when install speed rules; EZW 2–12 in.
→ 471 · 431 · EZWS
"PVC main — any joint at all"
PipeLock 472 couplings, FlangeLock 920 at the valves. PVC carries no thrust on its own; restrain everything or block everything.
→ 472 · 920
"Capping a line under pressure test"
EZWC seal & restraint line cap with its threaded test outlet — the dead end that holds itself on.
→ EZWC
"Valve setting without blocks or rods"
FlangeLock 911 (metal) or 920 (PVC); EZW-F when the flange type or laying length is special.
→ 911 · 920 · EZW-F
"Large-diameter restrained span"
477 restraint sleeve to 48 in; 923 for flange x MJ through 42 in.
→ 477 · 923
"The detail draws rods and plates"
Build it as drawn: 907 plates plus 101 rod sets in the diameters and lengths the thrust calc calls out.
→ 907 · 101
Straight Answers
Joint Restraint Questions
How do I know a joint needs restraint at all?
One question: if pressure pulled the pipe axially out of this joint, what stops it? Thrust blocks, anchored runs, or restrained joints elsewhere may already carry the load. Dead ends, bends, tees, unanchored PVC or PE, slopes, and test closures usually have nothing — those joints must restrain themselves.
Restrained coupling or thrust block — which is cheaper?
The block's concrete is cheap; its formwork, cure time, extended trench hours, and dependence on soil you can't inspect are not. On schedule-driven work the restrained coupling usually wins total cost, and it restrains in both directions while surviving future adjacent excavation — which the block does not.
Why are there different restrained couplings for DI, PVC, and steel?
Because grip is a contact-stress problem. Teeth that bite steel would damage PVC; a grip sized for PVC's allowable stress under-holds on iron; and OD standards differ by material. The 471/472/473 split exists so each pipe gets geometry engineered for its wall — one reason spec writers call PipeLock out by style number.
Does gripping restraint damage PVC pipe?
Not when the product is designed for it. PVC-rated designs spread engagement across multi-length teeth around nearly the full circumference, holding contact stress below the pipe wall's allowable — grip without crush. That is exactly why the PVC-specific 472 and 920 exist instead of one universal claw.
What about HDPE?
Only with internal stiffeners, always — the stiffener carries the radial loads the PE wall cannot, and each product lists its minimum DR. Send the pipe DR with the RFQ and the correct stiffener ships with the fitting.
When should I use the 907/101 harness instead of integral restraint?
When the specification draws it. Harness details remain standard on many municipal and plant drawings, and building the detail as drawn — 907 plates, 101 rods — is always the compliant path. Where the spec just says "restrained," integral restraint installs faster and inspects easier.
Can I restrain a transition between two different pipe ODs?
Yes — the PipeLock 473 handles restrained joints across unlike ODs, and the EZWR restrains true size reductions. Send both actual ODs and we confirm the configuration.
What do you need to quote a restrained fitting?
Pipe material and actual OD (both ends if they differ), working and test pressure, size, and the application — joint, cap, valve setting, or span. Configurations are verified against the factory catalog before anything ships; email sales@watermainsupply.com and quotes on stocked sizes go same-day.
Skip the Concrete. Restrain the Joint.
Engineering-led selection on every restraint product — pipe material, actual OD, pressure, and restraint method verified against the factory catalog before it ships. Smith-Blair and Dresser, stocked in Houston.
Email sales@watermainsupply.comOr call 281.664.8000 — same-day quotes on stocked sizes
Watermain Supply Houston, TX · watermainsupply.com
281.664.8000 sales@watermainsupply.com
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Authorized Distributor Smith-Blair (Xylem) · Dresser
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