NATREF’ Reliability and Maintenance teams collaborate together to increase reliability of their reciprocating compressors through use of Bently Nevada’s condition monitoring platform
Customer Type: Refinery
Industry: Oil & Gas
Application: Reciprocating compressor
Solution: BN3500 & System 1 (v19.1)
Overview
In an attempt to increase reliability and availability of their fleet of reciprocating compressors, NATREF’s Reliability team decided to equip their assets initially with basic protection measurements (in line with API 670 recommendations) to avoid any catastrophic damages resulting in expensive repairs and extended downtime; and then progress towards advanced predictive monitoring further optimizing maintenance cost.
Challenge
The main intent was to save the machines from any major damage and to proactively detect faults at their outset to plan maintenance effectively.
Conclusion & Resolution
As a trusted partner, NATREF has always sought domain expertise from Bently Nevada (BN) and the tradition continued when Bently Nevada’s Technical Leader for RECIPs visited NATREF to address their pain point(s) and collectively decided on the critical measurements for the pilot compressor for this initiative. NATREF’s experience with BN products (including sensors, monitoring system and condition monitoring platform) enabled them to carry out all engineering, installation and machine modification for sensor installation in-house (with recurring support from Bently Nevada’s Design and Installation Services – D&IS/Retrofit team).
Reliability team established the framework on retrofit in coordination with Maintenance and Instrument teams by optimally utilizing spare slots in existing 3500 rack and connecting to existing System 1 condition monitoring platform. In the first phase, it was decided to equip machine with API 670 recommended protection parameters comprising crankcase and crosshead vibration along with piston rod position and run out monitoring. Local BN D&IS Engineer visited site and decided optimal location & design for these sensors in coordination with Maintenance and Reliability teams. The calibration of sensors onsite and system configuration was carried out by BN RECIP Certified Engineer and was reviewed by Regional Technical Leader as per Quality Assurance process.
After box-up when machine was started, unusual high amplitudes were observed in crosshead vibration for stage 3. Reliability team consulted BN Recip Machinery Diagnostic Services (MDS) by sharing data; a detailed teleconference was conducted to identify the root cause. Based on data review it was concluded that head end (HE) suction valve (SV) and its unloader should be inspected for any possible issues since the vibration impacts were happening at HE SV opening event (@30 deg crank angle). Following inspection from Maintenance team, it was found that the HE SV was touching the unloader due to unloader stem being too long. Therefore, the clearance between the valve and the loader was adjusted to 2mm. Following the adjustment, compressor was restarted, and crosshead vibration was reduced back to normal. This showed the effectiveness of monitoring system which was able to capture faults occurring at cylinder while sensor was installed at crosshead (few meters away). Further with the domain knowledge of NATREF’s Reliability team and Bently Nevada, machine was brought back to healthy condition within a short period of 12 hours. Had this proactive approach not demonstrated by NATREF, the suction valve failure would have resulted in cylinder overheating eventually melting non-metallic consumables (packing rings, piston rings, rider bands etc.).
Authors
Ernest Ralidzhivha
E & I Systems and Instrumentation
NATREF
Fayyaz Qureshi
RECIP & Retrofit Technical Leader for MEIA
Bently Nevada
Basil Mkize
System 1 Technical Leader for Sub-Saharan Africa
Bently Nevada