Using SCADA Process Data to Optimize Preventive Maintenance

AutoSoft Systems

2 Round Hill Court

East Greenwich, RI 02818

401.885.3631

401.884.5653 Fax

401.996.3631 Cell

AMDG

Decision Ready Information!

autosoft@aol.com

Commercial & custom multi-user computer software for a variety of applications including performance metrics, statistical analysis, data extraction and merger from multiple large databases, computer simulation and management information systems. Founded in 1982.

We know Excel! Whenever possible, Excel is the user interface, VBA is the programming language, ODBC connects to the database of your choice.

Pharmaceutical & Biotech

Construction Management

AMDG

Using SCADA Process Data to Optimize Preventive Maintenance

Preventive Maintenance is a necessary function of every manufacturing facility. How much is too much? How much is too little? AutoSoft Systems has developed a suite of software tools that can be easily customized to assist in this decision at a variety of manufacturing facilities. Here is how it works:

The Acme Biotech Company has a large Bioprocess facility with thousands of diaphragm valves. Diaphragms wear out and need to be periodically replaced before they fail. Acme has a well-established process for periodically shutting down each system for a "Lock-Out Tag-Out" (LOTO) where all of the diaphragms in the valves are replaced. They rarely if ever have a diaphragm failure, so they do not want to mess with success. They do know, however, that not every valve experiences the same amount of usage. They would like to be able to determine the amount of wear and tear on each valve, and extend the replacement cycle on those valves that see lighter duty.

Diaphragms experience wear and tear when they are opened and closed and when they are subject to elevated temperatures. AutoSoft Systems extracted wear and tear information about each valve from Acme's SCADA (Supervisory Control and Data Acquisition) system and provided Acme's engineers with a slick, quick and easy to use interface to determine the wear and tear on each valve, and offer recommendations on the maintenance frequency.

The process starts with Acme's engineers identifying the "Tags" of each valve in the SCADA system and associated temperature sensors that indicate the temperature of the process stream that contacts the valve. In some cases, the temperature probe is located "one valve removed" from a valve, so that the elevated temperature event would only be experienced by a valve if both the temperature sensor records an elevated temperature AND another valve is opened.

AutoSoft builds an "AutoEvent" database that stores key information about each valve, including:

Associated Temperature Probe

Valve Sub-Type

PM Frequency

Subordinate Valve

Manufacturer

PM Form

Valve Description

Size

PM Last Completed

Valve Type

Diaphragm Material

Parent Asset

PM Number

The AutoEvent Compiler then dives into the SCADA database and extracts temperature history of each temperature sensor and records every on-off cycle of every valve.

Then the fun begins!

The AutoEvent Reporter allows the engineers to select any desired subset of the valves (or "Tags") in the AutoEvent database. Note that this example is for diaphragm valves. The AutoEvent process can also be applied to bearings, pumps, agitators, pretty much any piece of process equipment whose wear and tear can be captured by a SCADA system. Typically, the engineer will capture all of the Tags on a given skid or system that will be accessible and have historically been maintained during the same LOTO.

In this example, the Acme Engineer is looking for all valves in the 1420 System. 37 were found.

Once the desired list of Tags has been extracted (which takes only a few seconds), the engineer can then double click on any tag to extract the total "wear and tear" history of that tag. In the case of diaphragm valves, what is reported is time and duration of every "thermal" event (elevated temperature event), and the number of times the valve has been opened and closed, both at ambient and at elevated temperatures. Note how the engineer can specify a minimum "heating time". Specifying a non-zero heating time allows the engineer to filter out thermal events that are so short in duration that the diaphragm and valve never heat up, thus never experience any wear and tear.

What we see here is that the Acme Engineer picked valve "ACME-1420-37/CFM-OPEN.CV", which revealed a total of 30 thermal events for 2013, 29 of which exceeded the minimum threshhold time of 10 minutes. The event below the threshhold is gray. The valve was exposed to elevated temperatures a total of 30.95 hours. The valve was turned on while cold 609 times, off 581 time. While hot the valve was opened 29 times and closed 57 times.

The Acme Engineer can then double click on any one thermal event to view it's temperature profile, or highligh a number of thermal events to see all of their temperature profiles on the same graph. Here, 10 different thermal events are selected, note they do not have to be contiguous. This is the "Sequential" view, where each event is on a time line.

Note how each event is assigned a different color on the graph, and the corresponding color is indicated in the data set.

The "Overlay" option overlays the thermal events on the same graph.

The Summary Report allows the Acme Engineers to compare the wear and tear on each valve in the system. Note how the engineers can vary the point system, allowing them to vary the relative effects of thermal events and on-off cycles. The Summary report finds the valve with the greatest amount of wear and tear, and uses that as a benchmark. Any valve that experiences less than 1/4 of the wear and tear during the same time period as the benchmark valve is placed in the "green" category, those valves that only need maintenance on every 4th LOTO. Any valve exceeding 1/4 of the wear and tear of the benchmark but less than 1/3, is placed in the "blue" category, and can be maintained every third LOTO. Any valve exceeding 1/3 the wear and tear of the benchmark but less than 1/2, is in the "red" category and can be maintained every other LOTO. All other valves require maintenance every LOTO. In this example, the total amount of maintenance can be reduced by 41%.

The "+" sign opens additional columns of information to aid in the decision making process.

Again, note how the engineers can vary the relative point total. This tool is not a substitute for individualized PM decisions by a qualified engineer. What it does however, is provide "Decision Ready Information" to a qualified subject matter expert to help and accelerate the decision making process.

Contact AutoSoft Systems to learn how the AutoEvent tool can help you.

AutoSoft Systems | 2 Round Hill Court, East Greenwich, Rhode Island, USA 02818 | 401.885.3631 | Fax: 401.884.5653 | Mobile: 401.996.3631

This web page was last updated at 10/01/2014 02:45 PM and is written in EXCEL!