Dresser Style 31 Line Cap product photo

Dresser Pipeline Cap


Dresser Style 31 line caps close a plain pipe end on steel, cast iron and ductile iron pipe without welding or threading, rated 150 PSI in every size from 2 to 24 in. Order the steel or cast iron version by measured pipe OD, or use a line cap plug to cap through a Dresser coupling already on the pipe.



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Dresser Style 31 Line Cap - Steel Pipe, 2 in to 24 in
Dresser Style 31 line cap for steel pipe

Dresser

Free Shipping $499 or more

Dresser Style 31 Line Cap - Steel Pipe, 2 in to 24 in

From $345.33
Dresser Style 31 Line Cap - Cast Iron Pipe, 2 in to 24 in
Dresser Style 31 line cap for cast and ductile iron pipe

Dresser

Free Shipping $499 or more

Dresser Style 31 Line Cap - Cast Iron Pipe, 2 in to 24 in

From $430.51

Dresser Pipeline Cap

Dresser · Line Caps

Dresser Style 31 Line Caps and Line Cap Plugs

Bolted line caps that close a plain pipe end on steel, cast iron and ductile iron pipe, 2 in to 24 in, with no welding or threading. 150 PSI MAOP.

Dresser Style 31 line cap for steel pipe
150 PSIMAOP, all sizes
2 to 24 inSteel and iron pipe
1 in NPTVent standard
One gasketOne bolted follower

A Dresser line cap closes the open end of a plain-end pipe without welding a plate, threading the pipe or adding a flange. The Style 31 is built from Style 38 coupling parts: a dished steel head is welded into one end of the middle ring with its follower, so the cap needs only one gasket and one bolted follower on the pipe side. Crews use it to close sections during construction and pressure testing and to cap dead ends left for future branches. Line cap plugs do the same job inside a Dresser coupling already on the pipe.

The steel pipe and cast iron pipe caps are separate listings because the two pipes have different ODs. Every variant ends with the Dresser part number. Call 1-888.510.4036 or email sales@watermainsupply.com. Genuine Dresser equipment, factory-new in original packaging — sold and supported by Watermain Supply, an independent industrial supplier.

Will It Work for Your Job?

Pressure

Dresser rates the Style 31 at 150 PSI maximum allowable operating pressure in every size. Line cap plugs carry the rating of the coupling they sit in.

Thrust

A cap carries the full end thrust of the line pressure. Dresser requires anchorage or blocking that holds that thrust before the cap is pressurized.

Pipe

Order the steel version for steel pipe (2.38 to 24 in OD) and the cast iron version for cast and ductile iron (2.50 to 25.80 in OD). PVC C900 uses cast iron ODs.

Size It With Us

Send the pipe OD, pipe material and line content. We confirm the part number before you order. 1-888.510.4036 · sales@watermainsupply.com

Product Lines

Pick by pipe material, or use a plug if a Dresser coupling is already on the pipe.

Style 31, Steel Pipe

Style 31, Steel Pipe

Steel Pipe, 2 in to 24 in

Sizes2 to 24 in
MAOP150 PSI
GasketGrade 27
Vent1 in NPT

Bolted line cap for plain-end steel pipe, with a dished steel head and a fusion-bonded epoxy finish.

  • Vent centered on 2 and 3 in
  • No-vent and lock-pin builds to order
Best for Steel water and industrial lines
View Style 31, Steel Pipe
Style 31, Cast Iron Pipe

Style 31, Cast Iron Pipe

Cast Iron Pipe, 2 in to 24 in

Sizes2 to 24 in
MAOP150 PSI
OD2.50 to 25.80 in
Vent1 in NPT

The same cap sized to cast and ductile iron ODs, with two OD options on several sizes to match the pipe class.

  • Measure the OD to pick the class
  • Insulating design to order
Best for Cast and ductile iron water mains
View Style 31, Cast Iron Pipe
Line Cap Plugs

Line Cap Plugs

Style 1031 & 2090

1031With 1 in IPS vent
2090Without vent
FitsDresser couplings
InstallInto coupling

Plugs that insert into the open end of a standard non-insulating Dresser coupling to cap the line.

  • 1031: Style 38, 40, 62, 39-62, 2 to 6 in
  • 2090: Style 90, 3/4 to 1-1/4 in
Best for Capping with the coupling in place
View Line Cap Plugs

Compare the Line

Listing Sizes Rating (Dresser) Pipe Notes
Style 31 Line Cap, Steel 2 to 24 in 150 PSI MAOP Steel 1 in NPT vent
Style 31 Line Cap, Cast Iron 2 to 24 in 150 PSI MAOP CI, DI, C900 Two ODs on several sizes
Line Cap Plugs 1031 and 2090 3/4 to 6 in Per coupling Inside a Dresser coupling Vent or no vent
Style 711 Line Cap (gas) 2 to 12 in 150 PSI Steel, PE Seal and restraint
Style 711 Insulating Line Cap (gas) 3 to 8 in 60 PSI Cast iron Insulating
Quick rule: Open steel pipe end, use the Style 31 steel cap. Cast or ductile iron, use the Style 31 cast iron cap. Coupling already on the pipe, use a line cap plug. Gas main that must hold against pullout, use the Style 711 line cap.

Dresser vs Other Brands We Carry

Need Dresser Smith-Blair (also on our site) Verdict
Steel pipe end cap Style 31, steel Style 481 Comparable bolted caps; check vent and size
Cast iron line cap Style 31, cast iron Style 482 Both fit iron ODs; compare the OD range for your pipe
Restrained cap Style 711 line cap EZ-W line cap Both restrain; the 711 is built for gas PE and steel

We carry both brands. Send the pipe OD and material and we quote the better fit.

Selection Guide

Job Pipe Recommended
Close a section for pressure testing Steel Style 31, steel
Close a section for pressure testing Cast or ductile iron, C900 Style 31, cast iron
Cap a dead end for a future branch Steel or iron Style 31 for that pipe
Cap a line through an installed Dresser coupling 2 to 6 in Line cap plug 1031
Cap a Style 90 service fitting 3/4 to 1-1/4 in Line cap plug 2090
Cap a gas main with restraint Steel or PE Style 711 line cap

Sizing and Best Practices

Measure the OD

Use a pi tape on the pipe end. A 6 in steel pipe is 6.625 in OD; 6 in cast or ductile iron is 6.90 in and older cast iron can be 7.10 in. The cast iron listing offers both where Dresser builds both.

Prepare the pipe end

The gasket seats on a clean, round, plain pipe end. Remove scale and burrs where it seats.

Block for thrust

Install anchorage or blocking that holds the full end thrust of the line pressure before pressurizing the cap, as Dresser requires.

Use the vent

The 1 in NPT vent lets air out while filling and pressure out before removal. It is centered on 2 and 3 in caps and off-center from 4 in.

Need help? Send the pipe OD and material to sales@watermainsupply.com and we confirm the Dresser part number.

Why Engineers Specify It

No Welding

Bolts onto a plain pipe end.

One Gasket

Head and follower welded to the ring.

Vented

1 in NPT vent and plug included.

Epoxy Coated

Fusion-bonded epoxy finish.

Steel and Iron Sizes

Separate listings by pipe OD.

Part Number Ordering

Every variant ends with the Dresser part number.

Related Dresser Products

Dresser Style 38 Bolted Coupling - Steel Pipe, 1/2 in to 48 in

Style 38 Bolted Coupling

Steel Pipe, 1/2 in to 48 inViewDresser Style 38 Bolted Coupling - Cast & Ductile Iron Pipe

Style 38 Bolted Coupling

Cast & Ductile Iron PipeViewDresser Style 711 Line Cap - Seal and Restraint, Steel or PE Gas Pipe

Style 711 Line Cap

Seal and Restraint, Steel or PE Gas PipeViewDresser Grade 27 Buna-S Gasket - 1/2 in to 24 in

Grade 27 Buna-S Gasket

1/2 in to 24 inView

Genuine Dresser parts, listed by Dresser part number.

Why Buy From Watermain Supply

Engineering-Led Selection

We check pipe OD, material and line content against Dresser data before we quote.

Multi-Brand Honesty

We carry Dresser and Smith-Blair. If one is not the right fit for your job, we say so.

Order by Part Number

Every variant ends with the Dresser part number, so you get exactly what the spec calls for.

Account Terms

Net terms for contractors, utilities and municipalities on approved accounts.

Data Sheets on Every Listing

Dresser technical specifications and installation instructions are attached to each product.

Gulf Coast Service

Houston-based team for the Gulf Coast and nationwide shipping.

Frequently Asked Questions

What is a Dresser line cap?

A bolted cap that closes a plain pipe end without welding or threading. The Style 31 uses Style 38 coupling parts with a steel head welded into the middle ring.

What pressure is the Dresser Style 31 rated for?

150 PSI maximum allowable operating pressure in all sizes.

Does a line cap need thrust blocking?

Yes. Dresser requires anchorage or blocking that holds the full end thrust of the line pressure before the cap is pressurized.

Steel or cast iron version?

Order by pipe material and measured OD. Steel pipe takes the steel version; cast iron, ductile iron and C900 PVC take the cast iron version.

Does the Style 31 have a vent?

Yes, a 1 in NPT vent and plug come standard. Caps without vents, with lock pins or with an insulating design can be ordered.

What is a line cap plug?

A plug that fits into the open end of a Dresser coupling already on the pipe. Style 1031 has a 1 in IPS vent and fits Style 38, 40, 62 and 39-62 couplings from 2 to 6 in; Style 2090 fits Style 90 fittings from 3/4 to 1-1/4 in.

Can I use a line cap for pressure testing?

Yes. Closing sections during construction and testing is a main use, with the line blocked for thrust.

Is there a restrained line cap?

Yes. The Style 711 line cap seals and restrains on steel and PE gas mains.

What warranty applies?

12 months from the date of purchase under Dresser published warranty terms.

Can I get a submittal?

Yes. Email sales@watermainsupply.com with the part numbers.

Ready to Size Your Line Cap?

Send the pipe OD, material and line content. We confirm the Dresser part number and quote the same day.

1-888.510.4036Email SalesRequest a Quote
Technical data on this page is taken from Dresser product literature and is subject to change by the manufacturer. Confirm against the current installation manual before specifying. Dresser is a trademark of Dresser, LLC, used here for product identification only. Watermain Supply is a DBA of E4 Industrial LLC, an independent industrial supplier based in Houston, Texas.