For companies operating in the oil and gas equipment-manufacturing sector, comprehensive record-keeping and traceability are vital. As part of its company-wide quality protocol, FMC Technologies — based in Dunfermline, Scotland — has an on-going preventive maintenance programme that uses machine tool probes and calibration products to check and verify the dimensional accuracy of its CNC machine tools. Moreover, the resulting data is stored for quick and easy retrieval.
FMC Technologies is a Houston-based developer and manufacturer of oil and gas Production Control Systems. A PCS consists of top-side (surface) controls, power equipment, the Sub-sea Control Module (SCM), various sensors, and sub-sea electrical and hydraulic distribution equipment. The whole system is configurable for different conditions and requirements, and it provides engineers on-board an oil or gas production platform with precise control of the well.
FMC Technologies has operations around the world, near the major oil and gas industry operations. Its UK manufacturing operation occupies several buildings on and around the Pitreavie Business Park, Dunfermline. Craig Simpson and Mike West are FMC Technologies’ maintenance technicians, with responsibility for the service and support of 20 CNC machine tools of various types, makes and ages. Also in their charge is one of the company’s more recent investments — a £2.5 million purpose-designed SCM machining cell consisting of two Okuma Space Centre MA-600HB CNC horizontal boring machines that are loaded and managed by a Fastems automation system.
An SCM contains electronics, instrumentation and hydraulics for the safe and efficient operation of valves and chokes on the well-top ‘sub-sea tree’. Mr Simpson says: “There are four main machined parts in an SCM: one high-pressure adapter plate and a low-pressure one; the manifold block itself; and a base plate. There are also a large number of small valves and electronic circuit boards that go into the whole assembly.”
Defect-free production
Wells can be as far as 120km from the production platform, in water up to 10,000ft deep. Producing oil and gas safely and reliably under such conditions requires companies to make enormous investments. When an SCM is installed on the seabed, it has to be reliable and safe for the production life of the well, which can be decades. Hydraulically controlled valves must be free from defects and contamination.
If a critical part malfunctions, the potential cost can easily run to tens of millions of dollars — or even hundreds of millions of dollars. The Fastems automated cell is used to machine the stainless-steel hydraulic manifold block, which is a critical control element in an SCM assembly. The 267kg block is about 400 x 400 x 400mm and is a complex part that features some 350 drilled holes.
FMC Technologies will make more than 200 manifold blocks in 2014, when the cell is fully operational and capable of ‘lights out’ working. Should a tool break during the machining cycle, an NC4 laser-based tool-setting system from Renishaw plc
(www.renishaw.com) will detect the tool absence and notify the Fastems system, which will reject the pallet and replace it with another.
FMC Technologies is guided by what it calls the ‘five absolutes of quality’, the second of which emphasises the importance of “prevention, not appraisal” as the ‘cause’ of quality. “Quality control in the new cell is extremely thorough,” says Mr. Simpson. “The finished part is 100% inspected and has to be precise and flawless before it can be shipped to assembly.”
Performing to requirements
Because each SCM manifold block takes up to 35hr to machine, FMC Technologies’ engineers need to know that the Okuma machines in the Fastems cell are performing exactly as they should be. Scrapping a semi-finished or finished part due to an inaccuracy in the machine geometry would be very costly.
Mr Simpson says: “Traceability is everything; we have to be seen to be keeping precise records of our machining processes. We have to know if and when a machine is out of alignment, for any reason, so we can put it right. Then, when the problem is fixed, we have to be 100% sure that the machine is accurate again.”
To ensure that its 20 machines are accurate, FMC Technologies’ maintenance department services them up to three times annually. All machines are checked with a Renishaw QC20-W wireless ballbar. The Okuma machines are serviced twice a year, at which point machine geometries are checked and rectified. Once a year, the company also checks them with a Renishaw XL-80 laser measurement system and corrects any errors in linearity.
Every second year, at their annual service, all machines are levelled, aligned and again checked with the XL-80 system. Data from the Renishaw ballbar and the Renishaw XL-80 are collected and collated using Renishaw’s CNC Reporter software package.“During the routine service, we check each machine in the factory with the Renishaw ballbar,” says Mr Simpson.
“We keep those records so, should a finished or shipped part show a fault or a problem, we can prove whether the machine was accurate and aligned at the time the part was manufactured. In the event of an accuracy ‘issue’, we can also re-run the Renishaw ballbar, and compare the results with the records, to see how the dimensional accuracy of the machine has been affected.
“We use the Renishaw laser primarily to check linear dimensions. We also have Renishaw RMP60 touch probes on most of our machines, including the Okumas, so we need to know the linear movements are exactly right.” FMC Technologies initially invested in the CNC Reporter software primarily for keeping production records, but the company’s maintenance department has also found it invaluable and has recently invested in several additional licences.
Customised calibration
To help shorten machine checking and calibration times in the SCM cell, FMC Technologies has designed and built a custom calibration block that is mounted on the Okuma machines during scheduled maintenance or when the machine is being checked. “We are currently introducing a new pallet size in the SCM cell, and some of the re-programming is being done manually rather than off-line, using the Siemens NX CAE system. There is increased potential for minor collisions, and we recently had a small ‘knock’. First, we ran the Renishaw ballbar to check that the machine’s three axes were square. We also checked the Y axis using a test bar, then compared the results to the data in CNC Reporter. We found that the zero position had been affected, so we taught the machine new zero positions, using the test block.”
Messrs Simpson and West both agree that the Renishaw XL-80 laser measurement system, the QC20-W wireless ballbar and CNC Reporter software are very easy and intuitive to use. Mr West says: “We had one week of training with a Renishaw engineer. If ever we have a problem or a question, we call the head office in Gloucestershire, and we usually get an answer the first time. At the very least, someone calls
us back that day.”
FMC Technologies’ fifth ‘absolute of quality’ states that the goal of quality control is not customer satisfaction but customer success. The company claims that its Production Control Systems — along with its SCMs — are used on more than 1,000 sub-sea wells world-wide. Moreover, they achieve an up-time rate that exceeds 99%.
Nevertheless, Mr Simpson says the maintenance programme at FMC Technologies in Dunfermline is evolving continually: “When I first started at the company, six years ago, our preventive maintenance was far less structured and much more time-consuming. Now, we are very well organised, and using the Renishaw equipment means we know much more about our machines and our processes. We are always looking for ways to do things better. Our performance standard is zero defects, which is the third absolute in our quality philosophy. Nothing leaves this machine shop unless it is exactly right.”