China DN50 PTFE Lined Elbow Factory & Engineered Solutions

A Long Radius (LR) DN50 elbow features a center-to-face dimension of 1.5 times the nominal pipe size (approximately 76 mm or 3.0 inches per ASME B16.9), creating lower pressure drop, reduced turbulence, and decreased erosive wear from suspended particulates. A Short Radius (SR) elbow has a center-to-face dimension equal to 1.0 times the nominal diameter (50.8 mm / 2.0 inches). For highly corrosive and vacuum-prone fluid paths, LR elbows are almost universally preferred because the gentler bend curvature allows more uniform liner wall thickness distribution during paste extrusion and prevents localized thinning on the extrados.

Under sub-atmospheric pressures (vacuum distillation, vacuum reflux, or rapid cooling creating condensation vacuum), the pressure inside the liner drops below atmospheric pressure. Atmospheric air penetrating through vent holes or trapped gases behind the liner can push the liner inward, causing catastrophic radial collapse. Our DN50 fittings prevent liner collapse by utilizing high-density isostatic molding, thick-walled liners (≥ 3.5 mm minimum), interior mechanical anchoring (internal knurling/mesh grooves inside the steel housing), and tightly controlled sintering that eliminates liner delamination up to 200°C under full vacuum.

While PTFE is chemically impervious, small gas molecules (such as dry chlorine, bromine, or hydrogen chloride) can permeate through the fluoropolymer matrix at molecular levels over extended periods. Without vent holes, permeated gas accumulates in the annular space between the liner and the steel casing, creating backpressure that collapses the liner inward. Our elbows incorporate calibrated 2 mm to 4 mm vent holes fitted with porous PTFE vent plugs. These relieve permeated gases safely, prevent external rainwater intrusion, and provide immediate visual indication if a liner ever experiences catastrophic perforation.

In compliance with ASTM F1545 and DIN EN 14419, every single lined elbow undergoes a 100% non-destructive electrostatic spark test prior to dispatch. A high-voltage probe carrying between 14 kV and 20 kV direct current is systematically swept across the entire flared sealing face, interior throat, and extrados of the elbow. If microscopic pinholes, cracks, metallic inclusions, or voids exist, an electrical arc immediately discharges to the grounded steel shell, triggering an alarm. Defective fittings are rejected, ensuring zero leakage upon commissioning.

Yes. The flared PTFE face of the elbow serves as its own integral gasket, meaning standard rubber or sheet gaskets are typically unnecessary when bolting to flat-faced or raised-face mating flanges. However, when connecting to hard, uneven surfaces such as glass-lined nozzles or non-uniform metallic valves, specialized PTFE-envelope or microcellular expanded PTFE gaskets are recommended. Furthermore, star-pattern torque sequencing must be adhered to using calibrated torque wrenches to prevent crushing the flared fluoropolymer lip while ensuring a leak-tight seal.