Pigtail Syphon Tube 316SS

The stainless steel pressure gauge syphon (also called a siphon tube or cooling loop) is a critical instrumentation accessory used to protect pressure-measuring instruments from hot process media like superheated steam, as well as destructive rapid pressure surges. The unique loop design—whether an O-shaped pigtail coil or a U-shaped bend—allows the hot fluid to trap and condense inside the tube, forming a cool liquid barrier that isolates the internal gauge mechanism from direct thermal contact. Crafted from seamless, high-tensile stainless steel tubing, these syphons significantly extend the lifecycle and accuracy of gauges, switches, and transmitters in power, chemical, and steam piping applications.

Technical Specifications

• Product Form Configurations: Pigtail Type (O-Type), U-Type, and Multi-turn Coiled Type

• Tubing Material: 316L Stainless Steel / 304 Stainless Steel / Seamless Carbon Steel

• Inlet/Process Connection: 1/2" NPT Male, 1/4" NPT Male, or Welded Plain End

• Outlet/Instrument Connection: 1/2" NPT Female, 1/4" NPT Female, Swagelok-type compression nuts, or Swivel joints

• Thread Standards Supported: NPT, BSPT (PT), BSPP (G) dual compliance

• Tubing Manufacture: Seamless cold-drawn and fully annealed bend-forming

• Maximum Working Pressure: Up to 10000 psi (689 bar) depending on wall thickness schedule

• Maximum Working Temperature: Up to 450°C (842°F) for pure thermal isolation

• Tubing Outer Diameter (OD): 1/4" (6mm), 3/8" (10mm), 1/2" (12mm) standard options

• Wall Thickness Sizing: Schedule 40, Schedule 80, or heavy-wall Sch 160 configurations

• Cooling Efficiency: Lowers fluid temperature entering the gauge by up to 100°C per loop

• Dampening Profile: Naturally absorbs high-frequency fluid vibrations and heavy acoustic pulsing

• Bending Integrity: Uniform tube bending without localized wrinkling, flattening, or cross-section restriction

• Internal Volume capacity: Sufficient volumetric displacement to establish a stable condensate seal trap

• Surface Condition: Bright annealed internally and externally / Pickled satin sheen finish

• Applicable Equipment: Dial pressure gauges, electronic pressure transmitters, pressure relief switches

• Compatible Service Media: Saturated steam, superheated vapor, hot water, light oils, and process gases

• NACE Certification: Available to comply with NACE MR0175 for aggressive sour gas environments

• Pressure Isolation Testing: 100% pneumatic and hydrostatic proof pressure verified to ASME B31.1 / B31.3

• Traceability Protocols: Laser-etched heat number tracking directly marked on tube bodies