PRODUCTS
STYLE N / NS
Assets
Style N & NS couplings incorporate the more noble, duplex-alloy construction, which although initially more expensive, offers the superior corrosion resistance and corresponding better longevity for highly corrosive environments compared to the Style B coupling which is constructed from 316 alloy. Consult Piedmont application engineering for guidance on the selection of metal alloy for your application.
Application
Applications can impose severe-duty factors in addition to the maximum continuous operating pressure rating. These additional design requirements must be considered in selecting the appropriate Piedmont coupling.
+ Typical Applications
- SWRO desalination: Racks, seawater. UF modules. Concentrate & feed side of BWRO systems.
- Oil & Gas offshore platforms seawater treatment: sulfate removal units
Features
Working Pressure
450 psi (31 bar) for all sizes
+ Duplex (Style N) Housing
Duplex stainless steel type CE8MN (UNS #J93345) conform to ASTM A995, Grade 2A, PREN~35.
+ Super Duplex (Style NS) Housing
- Super duplex stainless steel type CE8MN (UNS #J93345) conform to ASTM A995, Grade 2A, PREN>40.
- Super duplex stainless steel type CE3MN (UNS #J93404) conform to ASTM A995, Grade 5A, PREN>42.
Other alloys are also available; contact Piedmont for details.
Hardware
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- Design
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- Standard components are iso metric thread type.
Bolts are round-head oval neck track bolts (own design based on DIN-5903)
Nuts are according to DIN-934 (ISO-4032).
Washers are according to DIN-125 (ISO 7089). - Optional:
Threaded rods (DIN-976) available upon request.
Inches series thread components available upon request.
- Standard components are iso metric thread type.
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- Gaskets
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- EPDM rubber, suitable for hot and cold water services. Peroxide cured manufactured to improve resistance against chloramines.
- Two shapes of gaskets are available: C-shaped or Flush-fit.
- NSF/ANSI 61 approved or equivalent (FDA) for drinking water system components. Not suitable for petroleum service.
- Other materials (Nitrile, Viton) are also available, contact Piedmont for details.
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- Design
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- Material
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- Standard: SS Duplex 2205 / S32205 as per ASTM A1082 (PREN>35). It is recommended to improve against chloride stress cracking, crevice and pitting bolts corrosion.
- Optional:
SS Super duplex 2507 / S32750 or S32760 (Zeron-100) as per ASTM A1082 (PREN>40)
SS316L bolts & SS316 nuts & washers as per ASTM A276 (PREN>23).
Silicon bronze nuts (ASTM B98 C65100) avoid the use of any additional antigalling paste on stainless steel bolts.
Antigalling / antiseize dry lubricated bolts/rods & nuts (Gleitmo 615 or similar).
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- Material
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- Isolation washer (optional):
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- In addition to duplex / super duplex material bolting upgrading, to improve against bolting crevice corrosion, some isolation washers are available upon request.
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- Isolation washer (optional):
Coatings (optional)
To improve against corrosion, couplings coatings components are available upon request:
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- Coated castings with epoxy primer plus polyurethane coating (other coatings available upon request).
- Coated hardware with fluoropolymer coats such as Xylan, Fluorokote or similar (Oil & Gas applications)
Quality
Standard Quality certificates
Piedmont is ISO 9001:2015 certified. The following quality certificates are provided with the order:
- EN10204 3.1 metallic components (castings, hardware)
- EN10204 2.2 certificate for EPDM gaskets
- EN10204 2.1 PO certificate of conformity
Quality tests (optional)
Several additional quality testing certifications with independent laboratories are available upon request:
| Optional test | Remarks |
|---|---|
| Hydrostatic proof test (1.5 x) | ASTM F1476 or ANSI AWWA C606 (in house) |
| Positive Material identification (PMI) | X-Ray fluorescent (XRF) |
| Dye penentrant test (DPT) | — |
| Corrosion test | ASTM G48 Method A ASTM 923 Method C ICG intergranular corrosion test (ASTM A262 Pract.B) |
| Metallographic / Micrographic analysis (incl. % Ferrite) | ASTM E562 |
| Bolts laboratory full analysis report | Grain flow, metallogr., hardness, etc. |
| Independent material and test certification (Oil & Gas applications) | EN10204 3.2 with GIS, SGS, Bureau Veritas, etc. |
| Magrographic / Macroetch alloy analysis | ASTM E340 |
| Impact (Charpy) test | ASTM A923 Method B or ASTM A370 |
| Hardness test | ASTM A370 |
| Ferroxyl test | ASTM A380 |
| Radiographic test | — |
| NORSOK qualified castings (Oil & Gas applications) | M-650 |
TABLE OF SPECIFICATION
| Nominal sizes: Inch (DN mm) | Pipe OD | X | Y | Z | Approx Weight | Working pressure* | Bolts & Nuts |
|---|---|---|---|---|---|---|---|
| inches (mm) | inches (mm) | inches (mm) | inches (mm) | lbs. (kg) | PSI (BAR) | Qty – size | |
| 2-1/2” (DN65) | 2.875” (73.03) | 4.99 (127) | 3.68 (93.4) | 1.70 (43.2) | 0.88 (0.40) | 450 (31) | 2 – M10 x 60 |
| 76.1 mm | (76.10) | 4.99 (127) | 3.68 (93.4) | 1.70 (43.2) | (0.41) | 450 (31) | 2 – M10 x 60 |
| 3” (DN80) | 3.500” (88.90) | 5.64 (143.1) | 4.26 (108.2) | 1.85 (47) | 1.09 (0.49) | 450 (31) | 2 – M10 x 60 |
| 3-1/2” (DN90) | 4.000” (101.60) | 6.45 (163.9) | 4.95 (125.7) | 1.92 (48.9) | 1.51 (0.68) | 450 (31) | 2 – M12 x 65 |
| 4” (DN100) | 4.500” (114.30) | 7.27 (184.7) | 5.56 (141.2) | 2.02 (51.3) | 2.05 (0.93) | 450 (31) | 2 – M14 x 80 |
Working pressure: Working pressures have been determined based on generally accepted standard specifications for performance of gasketed mechanical couplings, in accordance with ASTM F1476 and/or ANSI AWWA C606, and are applicable for schedule 40s pipes with cut grooves only. For use on pipes thinner than schedule 40s and for roll grooves, please consult with Piedmont. Pipe’s schedule, working pressure and material must comply with the requirements of ASME B31.1.
Images
NOTE
For the use of Style N couplings on cyclic axial displacement systems, please consult with Piedmont for design and installation guidance.
Quote request
Piedmont couplings are sold as a whole including the housing, the gasket, the bolts, nuts and washers when necessary. Please specify the coupling size and gasket type required.
Documents
Technical Drawing – Style N
Product Sheet – Style N
Coupling pipe groove
- Standard cut groove profile according to AWWA C606 table 4 for sizes up to 16”.
- Cut groove according to Piedmont specifications for sizes 18” and 20”.
- Please refer to the Installation Manual for further details on maximum allowable pipe displacements and angular deflections, coupling end loads, and roll groove.
- For SWRO high pressure applications, Piedmont recommends our couplings to be installed on pipe, and/or connecting fitting alloys with high corrosion & crevice resistance such as UNS S32750 & S32760 super duplex, S31254 and N08367 (PREN ≥ 40 & CF ≥ 35).
- For the use on cyclic axial displacement systems, please support properly the output high pressure flexible hose to avoid excessive bending loads, displacements and deflections on the grooves. They should work coplanar to avoid couplings damages. Consult with Piedmont for guidance.
Spare parts
- Recommended: gaskets and hardware kits.
- Castings components also available upon request.
- Consumable parts needed for assembly: glycerine lubricant for gasket, and, if so needed, antiseize/antigalling lubricant for SS bolts & nuts threads.
Complementary products
End caps, grooved elbows, Tees, pups/nipples, and others complementary grooved products are available. Please contact Piedmont for details.
