Description
STS7C-25 Stainless Steel Clamp Type Rigid Coupling – 25mm OD 316SS Corrosion-Resistant Split-Body Connector
The STS7C-25 clamp type rigid coupling is the 316 stainless steel version of the TS7C-25 aluminum alloy model. It retains the split-body clamp mechanism, bore range of 8, 10, rated torque of 1 N·m, and maximum speed of 4,000 rpm of the aluminum variant — the only change is the body material, which is machined from 316 austenitic stainless steel rather than aluminum alloy. The STS7C-25 weighs 79 g (compared to 2.8 g for the TS7C-25) and delivers the same non-marring, zero-backlash, repositionable shaft connection in environments where aluminum would corrode.
The STS7C-25 at 79 g provides 1 N·m rated torque at up to 4,000 rpm in 316 stainless steel, covering the 8–10 mm bore range of the mid-range precision coupling class. The clamp mechanism uses M3 screws — same as the TS7C-25 aluminum version — with a 10 mm hub length ensuring adequate shaft engagement for the 1 N·m torque level.
The stainless clamp mechanism is particularly valuable in food processing and pharmaceutical applications where the non-marring connection advantage of the clamp design and the corrosion resistance of 316SS are both required simultaneously — a combination that neither the aluminum clamp nor the stainless setscrew model addresses alone. Material certificates confirming 316SS grade are available on request. Full series listings are on our product catalog page.
Technical Specifications
| Parameter | Value |
|---|---|
| Model | STS7C-25 |
| Body Material | 316 Stainless Steel |
| Outer Diameter (D) | 25 mm |
| Overall Length (L) | 34 mm |
| Hub Length (L1) | 10 mm |
| Available Bore Sizes | 8, 10 |
| Clamp Screw Thread | M3 |
| Rated Torque | 1 N·m |
| Maximum Torque | 2 N·m |
| Maximum Rotational Speed | 4,000 rpm |
| Moment of Inertia | 7.4 × 10⁻⁶ kg·m² |
| Mass | 79 g |
Dimension Drawing
Stainless Steel Clamp Coupling — Dual Advantage
The STS7C-25 addresses two requirements simultaneously that no single alternative coupling design can match: (1) a non-marring, distributed-clamp shaft connection that protects precision shaft surfaces and allows repositioning during commissioning, and (2) a 316 stainless steel body that resists corrosion in food washdown, pharmaceutical, and wet industrial environments. Applications in these sectors often require both attributes — a stainless setscrew would still mark the shaft surface, while an aluminum clamp coupling would corrode in the operating environment. The STS7C-25 solves both constraints in a single component.
The 316 stainless steel alloy used in the STS7C-25 contains molybdenum (2–3%), which provides improved chloride pitting resistance compared to the more common 304 grade. This is specifically valuable in environments with sodium hypochlorite (bleach), chlorinated CIP solutions, sea water, and chloride-containing industrial chemical atmospheres where 304 stainless would develop pitting over time.
Typical Applications
- Food packaging servo encoder connections in wet zones where both stainless material and non-marring shaft contact are required
- Chemical process valve actuator position feedback — 316SS and non-marring clamp for hardened valve stem shafts in corrosive service
- Pharmaceutical tablet coating pan encoder — organic solvent atmosphere with precision motor shaft surface requirement
- Offshore platform process control instrument drives — salt spray environment with precision ground shaft surfaces
- Brewery and distillery process control servo drives — ethanol and CO2 atmosphere, CIP-cleaned equipment zones
Customer Reviews and Case Studies
★★★★★
Ireland — Food Packaging OEM
We manufacture vacuum skin packaging machines for premium beef and seafood. The STS7C-25 is our encoder coupling standard for all servo drives in the sealing zone — daily brine and CIP exposure makes 316SS essential, and the encoder manufacturer requires a non-marring clamp connection. Two years in service with no corrosion or shaft damage.
— Mechanical Engineer, Dublin
★★★★★
Norway — Offshore Engineering
Used in process control servo drives on a semi-submersible drilling platform. The 316SS body met our offshore material specification and the non-marring clamp was required because the encoder manufacturer’s warranty specifies no setscrew contact on their shaft. Installed for 20 months without service issues.
— Instrumentation Engineer, Bergen
★★★★☆
United States — Pharmaceutical Manufacturing
Specified for tablet coating pan encoder drives in an IPA-solvent atmosphere — the STS7C-25 was the only coupling meeting both our material (316SS) and shaft contact (non-marring) requirements simultaneously. Material certificates were provided with the order and accepted by our quality team.
— Validation Specialist, New Jersey
Frequently Asked Questions
Why choose STS7C-25 over STS7-25 or TS7C-25?
The STS7C-25 is the only option combining 316SS corrosion resistance AND a non-marring clamp connection. The STS7-25 is stainless but uses a setscrew (marks shaft). The TS7C-25 uses a non-marring clamp but is aluminum (corrodes in hostile environments). When both attributes are required, the STS7C-25 is the correct specification.
What bore combinations are available for the STS7C-25?
8 and 10 mm bore diameters on each side independently. Equal-bore (8/8 or 10/10) and mixed-bore (8/10) configurations are available at standard pricing.
Is the STS7C-25 dimensionally identical to the TS7C-25?
Yes. All dimensions are identical between the STS7C-25 and TS7C-25. The only difference is body material: 316 stainless steel versus aluminum alloy.
Is the STS7C-25 acceptable in EHEDG-certified food equipment?
316 stainless steel is an approved material in EHEDG design guidelines for food processing equipment. The smooth machined surface and absence of crevices in the clamp mechanism are also compatible with hygienic design principles. Confirm specific certification requirements with your compliance engineer.
Can the STS7C-25 be cleaned with peracetic acid?
316 stainless steel shows good resistance to peracetic acid at concentrations used in food and pharmaceutical CIP processes (0.1–0.3%). For higher concentrations or elevated temperatures, verify compatibility against published corrosion resistance tables for 316SS.
Source the STS7C-25 Stainless Clamp Rigid Coupling
Ever Power manufactures the STS7C-25 and the complete STS7C stainless clamp coupling series in-house, with 316SS material certification on request. Provide bore sizes, quantity, and application details for a factory-direct quote.
