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Dresser Style 39 insulating couplings join lines that must be electrically isolated for cathodic protection, or that join pipes of dissimilar metals. The insulating gasket has a skirt that runs under the follower to insulate it from the pipe, and a full-boot plastic insulator inside the middle ring keeps the pipe ends apart. The armored gasket on the other end bonds the coupling to that pipe so it can share cathodic protection current.
Application: Insulating joints on steel water, gas and industrial lines: tank hook-ups, intake and discharge lines, pumping stations, river and bridge crossings, and water heaters.
Included: one middle ring, two followers, one Grade 41 insulating gasket, one armored Grade 27 gasket, the plastic insulator and pipe end separator, bolts and nuts.
Pipe prepared before install: plain pipe ends, clean and round where the gaskets seat.
Anchoring, by others: the coupling seals but does not restrain.
Covered for 12 months from the date of purchase under Dresser’s published warranty terms.
From 150 PSI on 3/4 through 2 in to 900 PSI at 6 in, falling as diameter rises above that. The allowable pressure on a job also depends on the pipe, its condition and the workmanship.
| Nominal | Pipe OD (in) | Middle ring | Working pressure (PSI) |
|---|---|---|---|
| 3/4 | 1.050 | .120 x 5 | 150 |
| 1 | 1.315 | .134 x 5 | 150 |
| 1-1/4 | 1.660 | .140 x 5 | 150 |
| 1-1/2 | 1.900 | .138 x 5 | 150 |
| 2 | 2.375 | .154 x 7 | 150 |
| 3 | 3.500 | .156 x 7 | 350 |
| 4 | 4.500 | .188 x 7 | 350 |
| 6 | 6.625 | 1/4 x 7 | 900 |
| 8 | 8.625 | 1/4 x 7 | 750 |
| 10 | 10.750 | 1/4 x 7 | 600 |
| 12 | 12.750 | 1/4 x 7 | 550 |
| 14 | 14.000 | 3/8 x 7 | 550 |
| 16 | 16.000 | 3/8 x 7 | 450 |
| 18 | 18.000 | 3/8 x 7 | 400 |
| 20 | 20.000 | 3/8 x 7 | 300 |
| 24 | 24.000 | 3/8 x 7 | 300 |
Dresser Style 39 data sheet. Armored gasket on the conductive end.
| Followers | AISI C1012 or ASME SA36 (ductile or malleable iron for 3/4 through 1-1/2 in) |
| Middle ring | ASTM A513, ASTM A635 or ASME SA675 GR60 |
| Bolts | AWWA C111 / ANSI A21.11 |
| Gaskets | Armored-pinned Grade 27 Buna-S; Grade 41 on the insulating end |
| Coating | ID bare, OD fusion-bonded grey epoxy |
| Pipe end separator and insulator | Dresser Spec 100 plastic |
Source: Dresser Style 39 data sheet.
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