News & Insights from Dynaflow Research Group

Why Pulsation Risks Warranted Attention Before Operation The compression station was designed to increase and maintain operating pressure on a natural gas piping network, overcoming friction losses. It has four (3+1) two-stage centrifugal compressors with 19-blade impellers, running at a rated speed of 5750 RPM (95.8 Hz) within a range

A Commissioning Failure That Sent Debris Downstream During commissioning of a natural gas compressor station, pieces of fibreglass fabric, mineral wool and steel wire were found throughout the downstream system. A small amount of mineral wool was also found in the surge valve. Inspection showed that the mineral wool found

Compressor Piping Under Combined Marine and Process Loading The compressor module was located roughly halfway along the hull. Its connected piping had to accommodate thermal and pressure loads, wind loads, accelerations from wave-driven barge rocking and relative displacements from hull deformation. These loads could produce pipe deflection and bending and

Cyclic Thermal Duty in a Gas Treatment Air Cooler An air-cooled heat exchanger for a gas treatment plant is subjected to a varying inlet temperature. In the analysed winter case, which has the largest temperature variation, the fluid cycles between 7.5°C and 288°C during each 100-minute cycle. The first part

Consolidating Gas Flow onto a Single Metered Line A platform gas metering station has three parallel metering lines, two active and one spare. The modification replaces the orifice-type flow meter in the most eastern line with an ultrasonic (US) flow meter and directs the complete gas flow through that line.

Nitrogen Skid Stress Verification Requirement A manufacturer produces a nitrogen metering skid for a project. As a result of a client performance requirement, the existing design had to be verified by stress analysis. The skid is a straight pipe configuration with valves and flow meters, supported approximately 1000 mm above

An axisymmetric finite element analysis checked the flued flange expansion joint of a fixed-fixed tubesheet reboiler for low cycle fatigue, high cycle fatigue and primary stress to ASME Section VIII Division 2, at mean (26 mm) and minimum (22 mm) wall thickness. The largest low cycle fatigue stress range was

The station model of the Winksele Compressor Station, to be built in Belgium, was divided into two models with some mutual overlap, a compressor model and a filter model, each covered by a separate stress report. A third report covers the gas air coolers as model C, an add-on to

An additional separator was installed in Phase 2 of a cluster project and was to be connected to the existing lines through a modified above-ground (A/G) manifold. The manifold also connects to an existing buried (underground, or U/G) line. The analysis applied pressures of 100 / 225 Barg and temperature

A combined CAESAR II model of a gas metering skid and its structural steel frames was assessed against ASME B31.3 (2006). The piping stresses were below the allowables, the steel stresses were within the allowable limits for the sustained and expansion load cases, and several bolt shear loads exceeded the

Multi-Mode Metering Skid with Undefined Connecting Piping The unit assessed was a 24-inch, 300# ethane metering skid. Gas can be routed through a normal operating line (line 1), a testing and maintenance line (line 2), two flow control lines (lines 3 and 4) and a bypass. No more than one

CAESAR II stress analysis of 13 critical sections of a buried GRP fire water system, to ISO 14692, expected no problems for the underground piping under pressure and temperature loads. High stresses occurred in vertical above-ground GRP pipes where the pipe is vertically restrained; in section D, guide and rest

Seventeen underground GRE firewater subsystems at a degassing station were analysed in CAESAR II for three load cases, hydrotest, operational and sustained, to ISO 14692. It may be concluded that, upon implementation of the recommendations, the static pipe stresses are acceptable and the flange loads are moderate. Underground GRE Firewater

Thirteen buried GRE firewater subsystems were modelled in CAESAR II and assessed to ISO 14692 for hydrotest, operating and sustained load cases. On implementation of the recommendations, static pipe stresses are acceptable and flange loads are moderate. The buried glass-reinforced epoxy (GRE) piping in the firewater system upgrade at a

The main firewater line for a new oil terminal jetty is made from glass reinforced epoxy (GRE) pipe. It starts at the onshore transition between underground and above-ground pipe, where it connects to steel lines, and follows a jetty about 1.5 km long. A firefighting platform about one third of

Static stress analysis of two buried GRE firewater subsystems in CAESAR II covered three load cases with a design pressure of 13.4 barg and a maximum design temperature of 40 °C. The stress analysis report, a preliminary issue, records wall thickness increases and polystyrene on five isometrics and concludes that,

Nine underground GRE firewater systems, 77 stressed isometrics in total, were analysed in CAESAR II against the ISO 14692 allowable stress envelopes, with soil-pipe interaction modelled to the American Lifelines Alliance (2001) soil model. Modifications included a support bracing, polystyrene foam, NBR gasket stiffness limits and additional laminate for a

A CAESAR II static stress analysis of a buried GRE firewater network against ISO 14692 found 18 bends and 10 tees overstressed in the original design. In the modified models, all stress points are within the ISO 14692 envelopes for the sustained, operational and hydro load cases, provided the system

An underground storage station was being expanded with an additional compressor and a third injection well cluster, and the existing firewater package was being extended as part of the project. Two jockey pumps pressurise the system. When a blowout alarm is raised, the deluge valves open and the main firewater

A buried GRE fire water ring was assessed in CAESAR II against the ISO 14692 allowable stress envelope. Static stresses stayed within the envelope for all load cases after additional lamination at nine bends, and the settlement analysis set a 4 MPa axial margin on the operational or occasional envelope.

A new unit was added to an existing gas complex, and the firewater ring main was extended to serve it. Three sets of four 3-inch hydrant valves were modelled, twelve hydrants in total. Each hydrant is required to produce a minimum of 1452 l/min at 7.0 barg, and the hydrant