STYLE D / DS
STYLE D / DS
Style D & DS 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.
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.
An example of a severe-cyclical duty consideration is piping in the immediate proximity of the discharge of reciprocating, positive displacement piston pumps including the energy recovery devices of this type used in the seawater desalination industry.
Piping components, including grooved end pipe couplings, can be subjected to severe cyclical duty in industrial and desalination plants and engineers and designers need to assure that piping system pulsations and axial displacements are adequately provided for in the piping system design, particularly geometry.
Piping system displacements impart compressive and tensile loads in addition to the axial and hoop stresses arising from both continuous operating pressure and localized pulsation conditions. Displacement loads from reciprocating pumping devices impose additional stresses and require greater strength of the piping-joint components compared to piping components throughout the remainder of a plant at similar pressure, but not subjected to these additional loads. Contact Piedmont for assistance during the early stages of such designs.
1200 psi (82 bar) with schedule 40s pipe (special alloys) with cut groove only – all sizes.
+ Duplex (Style D)
Duplex stainless steel is highly resistant to chloride corrosion because of its metallurgy and microstructure. Used for high pressure couplings for seawater installation our duplex alloy is made of two metallurgical phases with each their role to play in the efficiency of the couplings.
Duplex 2205 is also available upon request. We highly recommend duplex for sea water corrosive applications.
• Austenite for nobility
• Ferrite for strength
The two phases are homogenized to form a metallic composite analogue to epoxy/glass composite. Our duplex is highly resistant to corrosion and offers twice the tensile and yield strength compared to stainless steel 316. Our duplex alloy is CE8MN and offers better mechanical properties when compared to conventional 316L stainless steel.
+ Super Duplex (Style DS)
Our couplings can also be produced using a Super Duplex material, which offers even higher corrosion resistance than duplex, and is very similar to alloys 2507 and Zeron 100 which are commonly used for seawater piping.
Made of Super Duplex stainless steel CE8MN alloy, our couplings are austenitic-ferritic stainless steel and highly resistant to chloride stress corrosion. Super Duplex grade of stainless also offers higher strength and better mechanical properties than duplex stainless steel.
As an option, these couplings can be specified with CE3MN Super Duplex material, which offers a slightly higher Pitting Resistance Equivalent Number (PREN).
To improve against corrosion, couplings coatings components are available upon request:
Standard Quality certificates
Piedmont is ISO 9001:2015 certified. The following quality certificates are provided with the order:
Quality tests (optional)
Several additional quality testing certifications with independent laboratories are available upon request:
|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|
|NORSOK qualified castings (Oil & Gas applications)||M-650|
|Style D/DS Specifications|
|Nominal size||X||Y||Z||Aprx Weight||Pressure rating*|
* Pressure rating when cut grooves and sch 40 pipes are used.
Note I: Working pressure ratings based upon generally accepted pressure piping design standards and testing in accordance with ASME Section VIII Division 1 pressure vessel test method.
Note II: It is allowed a single hydrostatic proof test at 1.5 x rating pressure before being put in operation at its rated pressure or less.
For the use of Style D couplings on cyclic axial displacement systems, please consult with Piedmont for design and installation guidance.
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.
Coupling pipe groove
End caps, grooved elbows, Tees, pups/nipples, and others complementary grooved products are available. Please contact Piedmont for details.