OS&Y stands for Outside Screw and Yoke. Unlike conventional butterfly valves where the stem threads are inside the valve body (exposed to the media), an OS&Y butterfly valve has the threaded portion of the stem located outside the body, enclosed in a yoke structure. This design provides three major benefits: (1) visual position indication — you can see whether the valve is open or closed by the stem position; (2) thread protection — stem threads are isolated from corrosive fluids, reducing galling and extending service life by 3–5x; (3) easier maintenance — you can lubricate and inspect threads without removing the valve from the line.

Both valves use the OS&Y (Outside Screw & Yoke) principle for the stem mechanism, but they differ in the internal closure element and flow characteristics. A gate valve uses a wedge that moves perpendicular to the flow path (linear motion), requiring multiple turns to open fully. A butterfly valve uses a rotating disc that opens with a 90° quarter-turn. Our OS&Y butterfly valve combines the visual position indication of a gate valve with the fast operation, compact footprint, and lower cost of a butterfly valve. For applications where space is tight and quick shut-off is needed — but you still want visible stem position — an OS&Y butterfly valve is the ideal hybrid solution.

Lead time: For standard sizes (DN50–DN300 / 2"–12") in ductile iron or carbon steel, production is 15–20 working days. For larger sizes or special alloys (316SS, Duplex), allow 20–30 working days.
Shipping to USA: Sea freight from Tianjin Port to Los Angeles / Houston / New York typically takes 25–35 days. We offer CIF (Cost, Insurance & Freight) pricing so you know the exact landed cost upfront. For a typical 20' container (approx. 120–200 valves depending on size), sea freight cost ranges from $1,800–$3,200 — significantly lower than air freight. We can also arrange DDP (Delivered Duty Paid) for qualified customers, handling all customs clearance and tariffs.

Yes — free samples are available for qualified engineering evaluation. We can provide one sample valve per size (up to DN200 / 8") with free shipping to your facility. You only cover any applicable local duties/taxes. Samples are fully tested and come with a complete documentation package (MTR, pressure test certificate, dimensional report). We encourage customers to conduct their own hydrostatic, cycle, and leakage tests. If the valve does not meet your performance requirements, we will refund the product cost — no questions asked. Contact our team to arrange your sample order.

Absolutely. We are a dedicated OEM/ODM manufacturer with over 12 years of experience serving valve distributors, engineering firms, and equipment manufacturers worldwide. Customization options include: • Custom flange drilling (ANSI, DIN, JIS, BS)
• Special trim materials (316L, Duplex 2205, Super Duplex, Monel K500, Hastelloy)
• Custom stem length & actuator mounting (ISO 5211, NAMUR, MSS SP-101)
• Private labeling with your brand, logo, and packaging
• Special coatings (PTFE, Nylon 11, Halar, epoxy)
• Third-party inspection (SGS, BV, Lloyds, TÜV)
Send your specification sheet or RFQ, and our engineering team will respond with a detailed proposal within 48 hours.

Our OS&Y butterfly valves are designed to meet ASME B16.34 pressure-temperature ratings and API 598 testing standards. For fire-safe applications, we offer configurations tested per API 607 (fire test for quarter-turn valves). Our valves are CE marked under the Pressure Equipment Directive (PED 2014/68/EU) and are manufactured in an ISO 9001:2015 certified facility. For US projects requiring UL/FM listing, please discuss with our team — we can arrange third-party certification per your project specifications. We regularly supply to US municipal water authorities and oil & gas facilities, and our documentation meets ASME Section II / Section VIII material requirements.