News & Insights from Dynaflow Research Group

A manhole interrupts the load-bearing shell of an elbow or tee, so the component is regarded as a non-standard piping fitting. The three fittings here are two 20 inch long-radius elbows, EX-23 and EZ-22, in SA-234 Gr. WP11 Cl. 1, and one 32 inch ASME B16.9 welding tee, FB-11, in

Furnace F-501 at a refinery heats crude through radiant coils made of A312 TP316Ti stainless steel. Each coil enters the radiant section at grade level, runs 21 loops parallel to the refractory lined furnace wall, crosses over to the roof section, makes 8 further loops against the roof, and leaves

Two identical Visbreaker bottom pumps at an onshore refinery were due for replacement. The existing pumps were of single side suction execution, the new pumps of double side suction execution. For the new pumps a minimum straight length of five times the diameter (5D) was specified directly upstream of the

A gas line between the high and low pressure separators of a hydrocracking unit failed in service, probably through material fatigue caused by vibration. An additional 3-way stop was fitted just downstream of the TSO valve to reduce vibration levels, and vibration was then measured at nine locations on the

The crude heating system serves one of two distillation trains: crude is preheated in a convection box, heated in the radiant section of the furnace and carried by a feed line to the tower. Crude heating generates two-phase flow, whose fluctuations impose the unsteady unbalanced loads at elbows and tees

At a refinery, a branch connection designated W31056, the 2″ line that ties in to the high-pressure steam attemperator J-3103 (a desuperheater), failed in service. A similar failure had occurred about twenty years earlier, in 1992. On-site observations report periodic movement of the connecting header, line 6″-S31022, which contains the

A refinery operator is replacing two existing steel main cooling water headers with Glass Reinforced Epoxy (GRE) piping. The two changes were raised as Technical Change Requests, and this case study covers the second of them, the “lube” cooling water header. The GRE consists of a header and a branch

A wash oil line was vibrating in the vertical section downstream of its angle control valve. It has been reported that the vibration amplitude increases with increasing flow, and in the future the mass flow rate may still be increased further. No vibration measurements had been carried out, so the

Undesirable vibrations were observed in the wash oil line between two vessels during activation of the wash oil flow, most severe in the vertical section immediately downstream of the angle control valve. An earlier study had already identified slug flow as the most probable cause and proposed mitigation measures, and

The 10″ inlet and outlet lines of furnace H301 carry two-phase content during all process conditions. Under certain process conditions, staff reported feeling like getting seasick when standing on the platform of the furnace, and the piping was seen vibrating mainly near the furnace. The impact of these dynamic effects

A flue-gas overhead line runs from a third stage separator to a waste heat boiler. It carries gas at a maximum operating temperature of 740 °C upstream of the orifice chamber and is designed for 755 °C in the hot-walled sections. At those temperatures the hot-wall material, stainless steel A240

Two existing steel cooling water headers were to be replaced with Glass Reinforced Epoxy (GRE) piping under two Technical Change Requests. This case study covers the first request, for the main cooling water header “boiler”. The second, covers the “lube” header. A flexibility analysis was required, together with recommendations, to

An 8-inch line carrying two-phase content from a heat exchanger to a gasoil stripper at a refinery had been vibrating for years, mainly in the two shorter horizontal sections, one downstream of the heat exchanger and one just upstream of the stripper. The operator had reported vibration for 5 to

A line in the creep range, where the weight loads set the support design The line studied here is the revised fluegas overhead line between the third stage separator and the superheater. It operates at 725 °C in the hot walled sections and 200 °C in the cold walled section,

A coil anchored at both ends, with the cross-over overloaded In a refinery furnace, the radiant coil carries crude. Under a project designated high TAN, the existing carbon steel radiant coil piping is to be replaced by stainless steel, grade A312 TP316Ti. This account presents the stress analysis of the

Lines assessed 4 Pipe content Two-phase gas-liquid flow, all process conditions Flow regime, start-up Slug flow Flow regime, normal operation Annular flow Pipe material A 358 type 321, main material Design temperature 400 °C Design pressure 77.5 bar, Lines 1 and 3; 81.0 bar, Lines 2 and 4 Liquid slug

Line temperature 700 °C Design temperature 755 °C Design pressure 4.2 barg Pipe material A 312 type 304H Allowable stresses ASME B31.3 Appendix A Expansion loop 4 inch, 6,000 mm deep Creep-range service on the catalyst withdrawal line A waste catalyst line runs from the regenerator to the waste catalyst