Coliter ® Standard Fully Welded Steel Ball Valve – Zero External Leakage for Buried Gas & Heating Pipelines
Standard Fully Welded Steel Ball Valve – PN25, DN50–200, Monoblock Carbon Steel Body for Direct Burial in Urban Gas and District Heating Networks
The Coliter® Standard Fully Welded Steel Ball Valve (Model: PN25, DN50–200) is a compact, high-reliability isolation valve engineered for permanent underground installation in urban gas distribution, district heating, and industrial fluid systems. Its body is fabricated from high-quality carbon steel and fully welded into a single, seamless unit—eliminating flanges, bolts, and gaskets to ensure zero external leakage, even under soil stress, seismic activity, or long-term burial. Rated at PN25 (2.5 MPa), it operates safely within a temperature range of -10°C to 180°C, with a sealing system composed of 20% carbon-fiber reinforced PTFE (RPTFE) seats and disc springs that maintain tight shut-off across pressure and thermal fluctuations—achieving 100% leak-free performance (0% leakage). The precision-machined stainless steel (304) ball ensures smooth, low-torque operation and full-bore flow for unrestricted media passage. Designed for direct burial, it requires only a small, shallow access chamber—significantly reducing civil construction costs and installation time compared to traditional valve pits. The valve body length and stem height can be customized to match pipeline design requirements. With a service life exceeding 15 years under normal operating conditions, this valve delivers exceptional durability, safety, and lifecycle economy for critical buried infrastructure.
Installation diagram
Product Description
| DN | Nominal diameter | DH | d | t | L | H1 | H2 | A |
| A/B | ||||||||
| 50 | 40 | 89 | 60.3/57 | 4 | 300 | 35 | 135 | 180 |
| 65 | 50 | 108 | 76.1/76 | 4 | 300 | 35 | 144 | 275 |
| 80 | 65 | 133 | 88.9/89 | 5 | 300 | 44 | 154 | 275 |
| 100 | 80 | 159 | 114.6/108 | 5 | 325 | 50 | 193 | 385 |
| 125 | 100 | 193 | 139.7/133 | 5 | 325 | 62 | 218 | 365 |
| 150 | 125 | 219 | 168.3/159 | 6 | 350 | 83 | 343 | 650 |
| 200 | 150 | 273 | 219/219 | 7 | 400 | 84 | 345 | 800 |
One body welded ball valve, free from external leakage and other phenomena.
Due to the fact that the valve seat is composed of carbon fiber reinforced Teflon sealing rings and disc springs, it has strong adaptability to pressure and temperature changes, and will not produce any leakage within the marked pressure and temperature range. The machining process of the sphere is tracked and detected by advanced computer detectors, so the machining accuracy of the sphere is high. Due to the fact that the valve body material, like the pipeline material, does not exhibit uneven stress, nor does it deform due to earthquakes or vehicles passing through the ground, the pipeline is resistant to aging. The sealing ring body is made of RPTFE material with a carbon content of 20%, ensuring complete leak-free (0%). Directly buried welded ball valves can be directly buried underground, without the need to build large valve wells. Instead, small shallow wells need to be installed on the ground, greatly saving construction costs and engineering time. The length of the valve body and the height of the valve stem can be adjusted according to the construction and design requirements of the pipeline. The machining accuracy of the sphere is very precise, with easy operation and no adverse interference. Using advanced raw materials, it can withstand pressures above PN25. Compared with products of the same specification in the same industry, the valve body is small and has a beautiful appearance. The service life of the valve should be over 15 years while ensuring its normal operation and use.
Use to
Urban gas: gas output pipelines, main lines, and supply pipelines for various branch lines.
Central heating: large heating equipment output pipelines, trunk lines, and branch lines. Heat exchanger: opening and closing of pipelines and various circuits.
Steel plant: various fluid pipelines, exhaust emission pipelines, gas and heat supply pipelines, fuel supply pipelines.
Various industrial equipment: various heat treatment pipelines, various industrial gas and heating pipelines.
Temperature pressure curve table
Materials of main parts
| No. | Component Name | Material quality |
| 1 | Valve body | Carbon steel |
| 2 | Ball | Stainless steel (304) |
| 3 | Ball pad | PTFE+20%C |
| 4 | Washer | 60Si2MnA |
| 5 | Valve stem | Stainless steel (SS301) |
| 6 | O-ring | FPM |
Product Inquiry
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Faq - Frequent questions
Introduction to Fully welded ball valve
Coliter®’s three-way ball valves enable precise flow direction control, mixing, or isolation in HVAC, process, and industrial fluid systems. The series includes the Q44F L-port (90°) three-way ball valve for switching flow between two outlets, and the Q45F T-port (straight-through) type for mixing or diverting flows from a common line. Available in manual (Q44F/Q45F), gear-operated (Q344F/Q345F), pneumatic (Q644F/Q645F), and electric (Q944F/Q945F) actuation, these valves feature forged brass, carbon steel, or stainless steel (304/316) bodies with PTFE or reinforced soft seats for bubble-tight shut-off (ISO 5208 Class VI). Rated at PN16 (1.6 MPa) and suitable for temperatures up to 180°C, they offer low torque, full-port flow, and reliable operation—ideal for chiller bypass, heat exchanger control, and dual-circuit distribution.
