style 31 line cap
style 31 line cap

Dresser Style 31 | Line Cap | Steel Pipe

Nominal Size: 2 in
Outside Diameter: 2.375 in
Middle Ring Length: 5 in

Product variant with selected options does not exist!
$368.48
SKU: 0031-0001-202
Weight : 11.0 lb
Free Shipping $499 or more
Need it fast? Call for same-day shipping options: 281.664.8000
Description
Dresser Bolted Line Cap

Style 31 Line Cap
Steel Pipe

Bolted slip-on end cap for plain-end steel pipe in nominal sizes 2 in through 24 in. Closes off pipeline sections during construction and testing, or permanently caps dead-end stubs for future branch extensions — no welding, threading, or pipe preparation required.

Sizes 2 in – 24 in
150 PSI MAOP All Sizes
1 in NPT Vent Standard
Built from Style 38 Parts
Insulating Version Available
Need to cap cast-iron pipe instead? Cast iron pipe has a different OD than steel pipe at the same nominal size. The Style 31 Line Cap for Cast Iron Pipe is sized to the larger CI ODs (Class A, B, C, D variations) — verify your pipe material before ordering.
View Cast Iron Version →
Overview

The Dresser Style 31 Line Cap for Steel Pipe is a purpose-built, gasketed end cap used to close off sections of a steel pipeline during construction and pressure testing, and to permanently cap dead-end pipe stubs for future branch extensions. Constructed from standard Style 38 coupling components with a convex dished steel head welded into one end of the middle ring, the Style 31 eliminates the need for blind flanges, threaded plugs, or field-fabricated end closures on plain-end steel pipe.

One follower ring is welded integral to the cap body, and only one gasket is required for installation. The cap slips over the pipe end and is tightened with standard coupling bolts, producing the same wedge-section gasket seal that makes the Style 38 coupling leak-proof under service conditions. Rated 150 PSI MAOP in all sizes; higher pressures available per application. The Style 31 is regularly supplied with a 1 in NPT vent and plug for air purging during initial fill and pressure testing.

Key Features
Tool-Only Installation
Gasketed slip-on design installs on plain-end pipe with standard coupling bolts — no threading, beveling, welding, or special tools.
Convex Dished Head
Steel convex dish welded into one end of the middle ring provides structural resistance to internal pressure loading across all sizes.
Built from Style 38 Parts
Same followers, gaskets, and bolt design as the proven Dresser Style 38 coupling. One follower is factory-welded to the cap; only one field-installed follower and one gasket required.
1 in NPT Vent Standard
Off-center vent and plug allows air purging and pressure equalization during filling and hydrostatic testing (2 in & 3 in sizes: vent in center of head). Caps without vents available on request.
150 PSI MAOP All Sizes
Rated 150 PSI Maximum Allowable Operating Pressure across the full size range. Higher pressures available per application — consult factory.
Armored Gasket
Grade 27 BUNA-S armored gasket with pinned-armor reinforcement for blowout and extrusion resistance under service pressure.
Fusion-Bonded Grey Epoxy
Factory-applied coating for corrosion resistance in buried and exposed service. Dresser RED-D Shopcoat finish available as an option — consult factory.
Insulating Design Available
Insulating version with insulating gasket, insulating sleeve, and pipe-end separator available for cathodic protection applications. Consult inside sales for project requirements.
Materials of Construction
Followers
AISI C1012 or ASME SA36
One welded to cap; one field-installed
Middle Ring (Cap Body)
ASTM A513 / A635 / SA675 Gr.60
Steel sleeve with welded dished head
Dished Head
Convex Carbon Steel
Welded into one end of middle ring
Bolts & Nuts
AWWA C111 / ANSI A21.11
Standard coupling hardware
Gasket
Grade 27 BUNA-S Armored
One gasket per cap; pinned-armor reinforcement
Coating
Fusion-Bonded Grey Epoxy
Dresser RED-D Shopcoat optional
Vent
1 in NPT with Plug
Off-center standard (center on 2 in / 3 in)
Insulating Option
Available on Request
Insulating gasket + sleeve + pipe-end separator
Engineering References & Downloads
Style 31 Submittal PDF
Official Dresser product brochure covering Style 31 Line Caps. Includes design rationale, materials of construction, dimensional diagram, and complete spec tables for both steel and cast iron pipe applications. For engineering review and project files.
Download Submittal
Pipe OD Reference Chart
Outside-diameter cross-reference for steel, PVC, polyethylene, ductile iron, cast iron (all classes), and asbestos cement pipe — sizes 1/2 in to 60 in. Verify pipe OD before specifying cap size.
Download Pipe Chart
Sizes & Specifications — Steel Pipe
Nominal Size Pipe OD (in) Middle Ring (Thick × Len, in) Bolts (No. × Diam × Len, in) Working PSI Ship Wt (lbs)
2 in 2.375 .188 × 5 3 — 5/8 × 6 150 12
3 in 3.500 .188 × 5 4 — 5/8 × 6 150 16
4 in 4.500 .188 × 5 4 — 5/8 × 6 150 19
6 in 6.625 1/4 × 5 6 — 5/8 × 8-1/4 150 28
8 in 8.625 1/4 × 5 6 — 5/8 × 8-1/4 150 37
10 in 10.750 1/4 × 5 8 — 5/8 × 8-1/4 150 39
12 in 12.750 1/4 × 5 8 — 5/8 × 8-1/4 150 47
14 in 14.000 1/4 × 7 10 — 5/8 × 10-3/4 150 73
16 in 16.000 1/4 × 7 10 — 5/8 × 10-3/4 150 86
18 in 18.000 1/4 × 7 12 — 5/8 × 10-3/4 150 98
20 in 20.000 3/8 × 7 12 — 5/8 × 10-3/4 150 113
24 in 24.000 3/8 × 7 15 — 5/8 × 10-3/4 150 187

All Style 31 Line Caps supplied with 1 in NPT vents as standard. Higher pressures available per application. Larger sizes available — consult factory for your particular requirements.

⚠ Seal Only — Anchorage or Blocking Required Under Pressure
Style 31 Line Caps provide a pressure seal only — they do NOT provide pipe restraint. Line Caps must NOT be used under pressure WITHOUT ANCHORAGE OR BLOCKING sufficient to withstand the entire longitudinal thrust due to internal pressure. Use thrust blocks, anchor straps, or restraint harnesses appropriate for your working pressure and pipe size before pressurizing the line. Failure to anchor the cap could result in cap blow-off, escaping line content, property damage, serious injury, or death.
When to Specify Style 31 vs Style 1031
The Style 31 Line Cap slips over the pipe end and seals directly to the pipe OD — use it when capping plain-end pipe (new dead-ends, retired services, hydro test closures). For sealing the open end of a previously-installed Dresser bolted coupling — commonly used where a coupling was preset for a future branch connection — specify the Style 1031 Line Cap Plug instead. Style 1031 is available in IPS sizes 2 in, 3 in, 4 in, and 6 in only. Consult inside sales for Style 1031 availability and pricing.
Consult Inside Sales For
Caps without vents, lock-pin caps for thrust restraint, insulating versions for cathodic protection, higher pressure ratings, sizes above 24 in, alternative gasket compounds, American Iron & Steel (AIS) or BABAA certification, all-stainless construction, or Dresser RED-D Shopcoat finish.
Ready to Order?
Confirm pipe OD, vent configuration, and any cathodic protection requirements before placing your order.
Shop Watermainsupply.com
281.664.8000
sales@watermainsupply.com
© Watermain Supply — A division of E4 Industrial LLC
Submittal

Style 31 Line Cap Submittal

Share E-mail

Related products