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Smith-Blair Pipe Repair Dismantling Joint | Expansion Joint
Smith-Blair Style 972 Dismantling Joint - 4 in to 72 in
Smith Blair
Smith-Blair Style 972 Dismantling Joint - 4 in to 72 in
- Price
- From $1,057
Smith-Blair Style 971 Dismantling Joint - 3 in to 16 in
Smith Blair
Smith-Blair Style 971 Dismantling Joint - 3 in to 16 in
- Price
- From $619.76
Smith-Blair Style 973 Restrained Dismantling Joint - 3-12 in
Smith Blair
Smith-Blair Style 973 Restrained Dismantling Joint - 3-12 in
- Price
- From $1,393.34
Smith-Blair Style 975 Restrained Dismantling Joint - 4-42 in
Smith Blair
Smith-Blair Style 975 Restrained Dismantling Joint - 4-42 in
- Price
- From $1,051.13
Smith-Blair Style 612 Expansion Joint - Double End, 3-24 in
Smith Blair
Smith-Blair Style 612 Expansion Joint - Double End, 3-24 in
- Price
- From $2,054
Smith-Blair Style 611 Expansion Joint - Single End, 3-24 in
Smith Blair
Smith-Blair Style 611 Expansion Joint - Single End, 3-24 in
- Price
- From $2,431
Smith-Blair Pipe Repair Dismantling Joint | Expansion Joint
Authorized Smith-Blair (Xylem) Distributor
Dismantling Joints &
Expansion Joints
3 in to 72 in
The two fittings that solve the two hardest problems in flanged and plant piping: getting valves, meters, and pumps in and out of a rigid flanged run — and living with pipe that grows, shrinks, and moves. Smith-Blair dismantling joints provide the longitudinal adjustment that makes flanged equipment installable and serviceable; Style 611 and 612 expansion joints absorb thermal movement before it becomes a stress fracture. Restrained and standard configurations, 3 in through 72 in.
3–72 in
Flanged Sizes Covered
6 Products
4 DJ Styles · 2 EJ Styles
Restrained
& Standard Options
Engineered
Verified Before It Ships
Education
What a Dismantling Joint Actually Does
Flanged piping is rigid by design — and that rigidity becomes the enemy the day a valve has to come out, or the day the as-built dimension doesn't match the drawing. A dismantling joint is a flanged fitting that telescopes: it adjusts its own laying length, closing the gap on installation and opening it again for removal.
The Two Problems It Solves
①
Installation — When As-Built ≠ Design
A flanged valve must land bolt-hole-to-bolt-hole between two fixed flanges. If the gap is even a fraction off — and in the field it always is — nothing mates. The dismantling joint's adjustable length absorbs the difference: telescope it to the actual gap, bolt both flanges, done. No cutting, no re-welding a spool, no waiting on a fabricated make-up piece.
②
Maintenance — Getting Equipment Out Alive
Ten years later, that valve needs service. Without a dismantling joint, removing it from a rigid flanged run means cutting pipe or spreading flanges under load. With one, you unbolt, collapse the joint's length, and lift the equipment straight out — then reverse the sequence to reinstall. Every serious pump station and meter vault design includes one for exactly this day.
③
Bonus — Angular Forgiveness
The telescoping design also absorbs small angular misalignments between the mating flanges — the kind that make solid spools fight the bolt holes.
Mechanically, a dismantling joint is a flanged spool nested inside a flange adapter: one end is a fixed flange, the other slides over the spool body and locks at the installed length with tie rods spanning the assembly. The rods do double duty — they set and hold the laying length, and on restrained models they carry pressure thrust across the joint.
Where They Belong
Pump suction and discharge headers. Meter vaults and backflow assemblies. Valve installations of every kind — butterfly, gate, check. Treatment plant yard and gallery piping. Anywhere a flanged component will someday need to come out faster than it went in.
Dismantling vs Expansion — Not the Same Fitting
Both change length, for opposite reasons. A dismantling joint is adjusted once and locked — a length-setting installation tool. An expansion joint is never locked — it moves continuously in service to absorb thermal growth. Specify by what the joint must do after installation day.
The Specification That Prevents Callbacks
Restrained vs Standard Dismantling Joints
A dismantling joint sits in the middle of a pressurized line — and pressure across its telescoping section generates thrust that tries to push the assembly apart. Whether the joint itself must carry that thrust is the first specification decision.
When a Standard Dismantling Joint Works
When the piping system already restrains the thrust: anchored equipment on both sides, restrained flanged runs, thrust-blocked fittings, or vault walls carrying the load. In a fully rigid, anchored flanged gallery — the most common pump-station case — the standard Style 971 or large-diameter Style 972 does the job economically.
When Restraint Is Not Optional
When the joint is the weak link in the thrust path: unanchored runs, connections to equipment that must not take pipe loads, buried or exposed spans without blocking, or any hydraulic condition where pressure can drive the telescoping section open. An unrestrained dismantling joint in an unrestrained line is a separation waiting for a pressure spike — specify the 973 or 975.
How the Restrained Versions Carry Thrust
①
Tie Rods Become Structure
On restrained models, the rods spanning the assembly are sized and detailed as thrust members: pressure load on the telescoping section transfers through the end flanges into the rods, which carry it in tension across the joint — the same engineering logic as harnessed tie-rod restraint on any sleeve coupling.
②
Rod-Restrained — Style 975
The full rod-restrained architecture, 4 in through 42 in: thrust carried end-to-end on the rod set, bidirectional, with the same telescoping adjustability for install and removal.
③
Cam-Lock Restrained — Style 973
Compact restraint on the 3 in to 12 in sizes using Smith-Blair's Cam-Lock locking system to secure the joint against pressure separation — the short-pattern restrained answer for tight vaults.
④
Still Fully Dismantlable
Restraint doesn't sacrifice the mission: release the rods and the joint collapses for equipment removal exactly like the standard versions — then restores full thrust capacity on reassembly.
Four Styles · 3 in to 72 in
The Dismantling Joint Line
Two standard styles and two restrained styles cover every flanged size from a 3 in meter setter to a 72 in transmission header.
Standard
971 & 972
Dismantling joints — thrust carried by the system
The economical choice for anchored flanged galleries. The 971 covers the distribution sizes; the 972 is the large-diameter workhorse, running all the way to 72 in for transmission mains, plant headers, and big meter installations.
- Style 971 · 3–16 inView product
- Style 972 · 4–72 inView product
Restrained
973 & 975
Restrained dismantling joints — thrust carried by the joint
Self-restraining across the telescoping section: Cam-Lock on the compact 973, rod restraint on the 975 through 42 in. The specification default whenever the surrounding system can't be proven to carry the thrust.
- Style 973 · Cam-Lock · 3–12 inView product
- Style 975 · Rod restrained · 4–42 inView product
Also Stocking Dresser
We carry the Dresser Style 131 dismantling joint line alongside Smith-Blair — if your spec is written around the other brand, send it over and we quote the compliant equivalent with the best lead time.
Thermal Movement · Styles 611 & 612
Expansion Joints — 3 in to 24 in
Pipe moves. A steel line's length changes with every degree of temperature swing, and in exposed runs, plant yards, and long galleries that movement has to go somewhere — either into an expansion joint built to absorb it, or into flange bolts, equipment nozzles, and pipe supports that were never meant to take it.
Single End
611
Expansion joint, single-end travel · 3–24 in
One slip end absorbs axial movement in a packed, serviceable telescoping design. The standard answer where movement is moderate and one anchor point defines the run — the joint installs near the anchor and takes the growth from one direction.
- Sizes 3–24 in · multiple travel optionsView product
Double End
612
Expansion joint, double-end travel · 3–24 in
Slip ends both sides — twice the travel in one fitting, taking movement from both directions. The choice for long runs between anchors, larger temperature swings, or wherever a single-end joint's travel budget runs out.
- Sizes 3–24 in · multiple travel optionsView product
Expansion Joints Do Not Restrain — Anchor the Line
An expansion joint is deliberately free to move axially, which means it carries no thrust and controls no pipe position by itself. Proper anchors and guides are part of every expansion joint installation: anchors fix the run's ends, guides keep the pipe aligned into the joint, and the joint absorbs what moves between them. Skipping the anchors turns thermal design into a slow-motion failure.
Spec It Right the First Time
How to Order a Dismantling or Expansion Joint
These are configured, engineered fittings — five numbers specify one correctly. Send them with your RFQ and the quote comes back right the first time.
1 · Nominal Size & Flange Standard
Pipe size plus the flange drilling it must mate — AWWA/ANSI class and any special drilling. Both ends if they differ.
→ Size + flange class
2 · Face-to-Face Dimension
For dismantling joints: the actual gap between mating flanges, measured in the field — the joint's adjustment range is chosen around it. As-built beats the drawing every time.
→ Measured, not assumed
3 · Working & Test Pressure
Determines pressure class and, on restrained models, the rod sizing. Include surge conditions if the line sees them.
→ WP + test
4 · Restraint Requirement
Is thrust carried by the system (971/972) or must the joint carry it (973/975)? For expansion joints: confirm anchors and guides exist in the design.
→ The callback preventer
5 · Service & Coating
Potable, wastewater, buried or exposed — drives coatings and hardware selection. For expansion joints, add the temperature range and required travel.
→ Environment
All Six, One Table
Dismantling & Expansion Joint Comparison
| Style | What It Is | Restrained | Sizes | Length Behavior | Reach For It When |
|---|---|---|---|---|---|
| 971 | Dismantling joint | No | 3–16 in | Adjusted at install, then fixed | Valve/meter/pump installs in anchored flanged runs, distribution sizes |
| 972 | Dismantling joint, large diameter | No | 4–72 in | Adjusted at install, then fixed | Transmission mains, plant headers, large meters — to 72 in |
| 973 | Restrained dismantling joint, Cam-Lock | Yes | 3–12 in | Adjustable, restrained in service | Compact restrained installs in tight vaults |
| 975 | Restrained dismantling joint, rod type | Yes | 4–42 in | Adjustable, restrained in service | The specification default when the joint must carry thrust |
| 611 | Expansion joint, single end | No — anchor the line | 3–24 in | Moves continuously in service | Thermal movement from one direction, near an anchor |
| 612 | Expansion joint, double end | No — anchor the line | 3–24 in | Moves continuously in service | Long runs, big temperature swings — double the travel |
Dismantling joints are length-setting fittings: adjusted at installation, locked, and reopened only for equipment removal. Expansion joints move continuously and require anchors and guides in the piping design. Restrained models carry pressure thrust across the joint; standard models rely on the system to carry it.
Straight Answers
Dismantling & Expansion Joint Questions
What's the difference between a dismantling joint and an expansion joint?
Purpose after installation day. A dismantling joint is set to length once and locked — it exists so flanged equipment can be installed to the real field dimension and removed later. An expansion joint is never locked — it moves continuously to absorb thermal growth. If the joint must move in service, it's an expansion joint; if it must adjust once and hold, it's a dismantling joint.
Do I really need one at every valve?
Any flanged component you ever intend to remove needs a removal path. Without a dismantling joint, that path is cutting pipe or spreading loaded flanges. One 971 per valve assembly is cheap insurance against a future confined-space cutting job — which is why modern pump station and vault standards draw one in.
When do I need the restrained version?
When pressure thrust across the joint isn't carried by something else. Anchored equipment, restrained flanged galleries, or thrust blocking on both sides: standard 971/972 works. Unanchored runs, buried spans, or equipment that can't take pipe loads: restrained 973 or 975. When the thrust path is unclear, restrain — the price difference is smaller than one separation.
How much adjustment does a dismantling joint give me?
Each size carries a designed adjustment range around its nominal laying length — enough to absorb normal field variance and open a removal gap. That's why the face-to-face dimension you measure matters more than the one on the drawing: we select the configuration whose range brackets your actual gap.
Single-end or double-end expansion joint?
Travel budget. The 611 absorbs movement from one direction — right choice near an anchor with moderate swing. The 612 doubles the travel and takes it from both directions — long runs between anchors and bigger temperature ranges. Calculate expected growth from run length and temperature swing, then pick the joint whose travel exceeds it with margin.
Why do expansion joints need anchors and guides?
Because the joint is the one deliberately weak axial point in the run. Anchors define which pipe moves toward it; guides keep that pipe aligned so the joint sees pure axial travel instead of binding sideways. An expansion joint without anchors doesn't control movement — it just relocates it to your flange bolts and equipment nozzles.
Can a dismantling joint correct misalignment?
Small angular misalignment between mating flanges, yes — the telescoping design absorbs what would make a solid spool fight the bolt holes. It is not a repair for genuinely misaligned piping; guides and supports still matter.
What do you need from me to quote one?
Five things: size and flange class, measured face-to-face (dismantling) or required travel and temperature range (expansion), working/test pressure, restraint requirement, and service environment. Email them to sales@watermainsupply.com — configuration is verified against the factory catalog before anything ships, and factory submittals are available on request.
Measure the Gap. We'll Configure the Joint.
Engineering-led selection on every dismantling and expansion joint — size, flange class, face-to-face, pressure, and restraint 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
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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