Take a look at some of our success stories

Sudden welding ruptures on minor branches

• high vibrations since the first start-up
• skid design failed to consider alternating forces
• poor support design

Acoustical study revealed the need for:

• restriction orifices
• new support installation

Unexpected trips for gas leakage

• welding ruptures of the inlet nozzle on piping
• acoustic resonance and poor piping clamping

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• installation of restriction orifices
• stiffening of the existing piping structure
• optimization of clamps disposition

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Rod packing elements life was <1000 hours

• recurrent rod scratching
• chromium on the rod surface

• roughening treatment to increase the transfer film capacity
• suggested high performance PEEK material

Ruptures on cooler and HP piping (every 2-3 months)

• high vibrations (up to 250 mm/s rms)
• modifications to be performed in one week

• FEM study of the mechanical system to define modifications to existing supports and structure
• foundations reinforced through grouting
• follow-up survey to confirm root cause analysis and resolution

High vibrations since first start-up

• vibrations above SWRI danger curve in some points
• acoustic analysis verified through strain gage measurements
• both acoustic and mechanical resonances found

• inserted restriction orifices in key points
• modified supporting structure to shift MNF
• inserted fabric pads between clamps and pipes

Client wanted to change driver type from gas engine to electric motor

Design of the new train arrangement with:

• Brake and Starting torque Analysis
• Torsional Analysis
• New coupling and flywheel selection

On site installation and commissioning through Blackstone (CST Canadian partner)

Extremely fast rings consumption

• rings provided by OEM failed after less than 100 h
• major damages to pistons and liners due to inadequate protection system
• alternate material from OEM’s competitor lasted for 1500 h

• new lubrication system
• improved cylinder cooling system
• stronger material (PEEK) with optimized dimensions
• new piston design

Frequent piping support failure

• inadequate type and position of supports
• piping weight applied on compressor flange
• wood layer between steel supports

• FEM analysis to find better supports design
• new “spring type” supports
• new antifriction damping layer between steel supports

Impeller destroyed twice at first Start-up

• RCA with rotor-dynamic and metallurgical analyses revealed wrong clearance on bearings
• New bearing arrangement defined and installed

Turbine trip during start-up on both units. Severe damage to the rotors due to rubbing against the stator

• RCA indicated casing bow (non uniform expansion), resulting from an insufficient thermal insulation of the casing
• Re-calculation of the thickness of the thermal insulation
• Suggested new procedure for turbine warm-up
• Revised seal radial clearance

After a maintenance stop, Turbine could not start due to high vibrations (both low and high frequency)

• RCA results: not appropriate bearing clearances and oil inlet design
• Bearings replaced with 4-lobe types (low-frequency vibration)
• Trim balancing (for synchronous vibration)

Gas leakage between upper and lower semi-casings

• RCA indicated a reduction of contact pressure due to corrosion and wrong maintenance
• Static FEA to determine contact pressure distribution
• Increased stud bolts diameter, added new tie rod

Up on a temporary strainer quickly rose to ~1.3 bar

• Customer could not stop production before scheduled maintenance

• Finite element analysis and a buckling analysis
• Maximum sustainable pressure drop ~ 4 bar

Performance improvement through upgrading of an old unit which has at present:

• High vibration levels upon certain process conditions
• Missed production targets due to high absorbed power
• High bearing temperature on gearbox

• Site survey, gathering data from personnel & DCS
• Action list including upgrade on seals, balancing drum and gearbox bearings
• Study possible efficiency increase to improve plant productivity

Performance loss (efficiency and flow rate) caused by  increased clearance between impeller and casing due to corrosion

• Labyrinth seal insertion
• Clearance reducion

Catastrophic failure of stirrer supporting bearing caused heavy damage to the reactor wall

• RCA revealed too little elasticity in bearing clamping system
• New clamping system developed

Explosion of the Gas Turbine cabinet

• RCA results: not appropriate bearing clearances and oil inlet design
• Bearings replaced with 4-lobe types (low-frequency vibration)
• Trim balancing (for synchronous vibration)

Old PtP lubrication system with recurrent issues

• Faulty sight glasses
• Unstable lubrication (dry run occurred)
• High oil consumption

• 5 units retrofitted with CST PLS-100 (full redundant + continuous monitoring)
• Reduced oil consumption recovered the investment in less than one year

Unexpected compressor shutdown

• Cross-head pin failure
• Crank-mechanism lubrication oil polluted by metal particles
• Delivery valves failures (cracked guard)

Root Cause Analysis based on:

• Visual and metallographic inspection
• Stress and fatigue simulation by means of FEM Analysis assessed sudden overpressure caused by liquid slug ingestion

Recurrent high vibration on a variable speed compressor

• RCA revealed correlation between rotation speed and MNF
• Speed variation limited to safe range

Two cylinder-distance piece tie-rods found broken

• High cylinder vibrations
• High pin load caused by suction pressure higher than design

• 2nd stage cylinder bore diameter modified
• High-resistance rolled thread tie-rods
• Volume bottles size increased

Knocking sound from cylinder head

• Piston-to-rod connection found loosened

• Trend analysis to highlight possible overpressures
• Visual inspection and measurements revealed an “out of tolerance” dimension of rod to piston connection
• FEM Analysis carried out on mating areas confirmed a tightening fault during assembly

Foundation corruption

• Cracks on the foundation walls
• Inefficient stiffeners
• High vibrations

Complete turn-key project

• Excitation reduction adopting a different crankshaft design. Engineering completed with:
• Dynamic analysis for unbalanced forces and couples
• Acoustic analysis for pulsations
• Foundation re-engineered
• Old Foundation demolition and refurbishment

• Fretting phenomena on the back side of connecting rod bearings and conrod body
• Big end casted aluminum bearing failure

• RCA to assess the cause of the failure and confirm the fretting phenomena by FEM simulations
• Big end bearing, studs and body reverse engineering and redesign to optimize contact pressure and avoid relative movement between bearing and big end

• Determine the source of piping vibrations
• Apply effective modifications to reduce them below the recommended values

• Identification of a source of flow induced vibrations in a Tee junction
• Flow modelling to characterize the source of vibrations and the pulsation phenomenon
• Piping FEM modelling to determine mechanical natural frequencies
• Multiple solutions identified to find the best compromise between vibration reduction and cost of modifications

• Determine the source of 1st stage side vibrations, causing continuous alarms and machine blocks
• Apply effective modifications to reduce them below the recommended values

• On site vibration detection
• Data analysis found a dominant frequency that characterizes the totality of plant components – 1st stage Pocket Pass Frequency
• Countermeasures design focusing on the pipe affected by resonance phenomena
• Torsional analysis of the screw compressor train

• The compressor ran at 80-90% capacity most of the time
• The exceeding capacity is recycled to the compressor inlet and compression energy is wasted

• “Flux-to-Flow” system designed and installed on 1st stage
• Compressor thermodynamic and torsional behaviour verified for reliable and safe operation

Increasing vibration trend suggested machine stop and inspection: resilient element found heavily damaged

Major compressor failure prevented by substituting resilient element

Forced maintenance every 3 months due to fast wearing of PTFE piston sealing elements

• high performance PEEK material suggested
• scheduled temperature monitoring program

OEM no longer available. User wanted to extend the operating life of this old unit by upgrading machine monitoring

• Design and implementation of mechanical modifications to house new sensors
• Supply and installation of a new vibration monitoring cabinet, linked to the plant DCS

During the commissioning on the test bench of a high speed permanent magnet electric motor, severe vibrations were experienced

• A detailed lateral analysis, confirmed by a hammer test, showed that that the first critical speed was within the operating range
• The rotor was redesigned and the shaft stiffened to avoid to be close to a resonance.