Management of Change Replacement In Kind Exemption
According to the PSM regulations “The employer shall establish and implement written procedures to manage changes (except for ‘replacements in kind’) to process chemicals, technology, equipment, and procedures; and, changes to facilities that affect a covered process.” [1, par. (l)]
If a potential changes can be classified as replacements in kind, then the cost, time and effort of conducting the MOC business process can be completely avoided. Completely avoiding a business process is the ultimate cost reduction, and therefore a significant best practice.
Obviously, it’s important to have a clear understanding on just what, exactly, is a replacement in kind, often abbreviated, “RIK”.
What is Replacement In Kind?
OSHA provides the simple definition, “Replacement in kind means a replacement which satisfies the design specification.” [1, par (b)].
The design specification began with the design intent for the process, and was initially expressed in the design documents that were created at the time the process unit was first designed. The design intent was expanded and detailed in the design calculations. The original design intent was provided by the process designers to the plant operator, historically, in the form of paper in binders. These were known by various names: design documents, data books, engineering data books, and sometimes even green books or blue books depending on the color of the binders.
The design intent was further detailed in drawings and supporting documentation: P&ID’s, PFD’s, instrument lists, instrument spec sheets, etc.
No design activity has the bandwidth to define all the design standards, so industry standards are incorporated into the design specification by reference. Common examples include the ASME Boiler and Pressure Vessel Code, various ASTM material standards, ISA standards, etc. Additional engineering standards may also be incorporated by reference, whether they originate from the process designers or the plant operator.
Collectively, these items all constitute the design specification for a process. Furthermore, this could be considered the original design specification, since it existed at the time the process unit was designed.
There is no indication that procedures, whether for installation, operations or maintenance, are included in OSHA’s definition for design specification, although procedures do play a role in RIK definition.
Design Specification Lifecycle
A process unit’s configuration is not static—if it were, there would be no need for an MOC process. A process unit is constantly undergoing change from the following change agents:
- Management of Change instances
- Projects undertaken to enhance the unit, often called capital projects due to the way they are classified in the company’s accounting system,
- Turnarounds: routine major maintenance activities, in theory, but in practice enhancements to the unit are always a part of turnarounds.
Any of these change agents may necessitate changes to the design specification. Also, periodic PHA revalidation may also cause changes to the design specification. Of course, in an operating plant, the change agents don’t just act once: they can act many times as indicated by the feedback loop in Figure 1.
All of the PSM elements contribute to safe operation of the plant, and up-to-date plant configuration information. So, if any qualification to OSHA’s term design specification can be justified, it would have to be that OSHA intends the current design specification to be the correct source of the RIK definition.
Figure 1. Design specification lifecycle
Broad or Narrow?
In order to achieve best practice, the creation of design specifications is a delicate balancing act. If the specifications are too broad, they may be inadequate and therefore unsafe: simply stating 3” pipe is far too broad, since the short- or long-term failure of pipe, under a given set of loads, depends on wall thickness, material properties, surface finish, exterior treatments, and so on.
In order to avoid the risks of specifications that are too broad, some designers overspecify the design, thereby narrowing the choice of parts and suppliers. A common example is to specify a manufacturer or preferred supplier. The problem is that if the part is not available from the specified manufacturer/supplier, then the part in question is immediately not a replacement in kind. This raises costs, since MOCs are now needed to qualify a part, that would have been allowable if the design specifications were more broadly written.
At times it is necessary to specify the manufacturer, and/or preferred suppliers. This is particularly true with more complex parts. In some cases the parts are so complex that the design specification is simply a copy of a vendor’s documentation—the so-called Vendor Drawing or Source Control Drawing. These are certainly the proper practices for particularly complex parts. However, the habit of using vendor-specific drawings should not be extended to simple, commodity items, since it may call for unneeded MOCs , as described above.
Identifying Replacement In Kind Based on the Design Specification
The design intent for the process unit was documented in the original design specification which was formally updated, as needed, to yield the current design specification.
Extensions to the Design Specification
The current design specification is necessary but not sufficient to operate and maintain the plant. Additional documents (e.g. operating procedures) must be created to facilitate the day-to-day activities in the plant. Although these additional documents elaborate, extend or specialize the current design specification, they must at all times be consistent with the current design specification. As a result, activities which satisfy the requirements of these additional documents, logically and reasonably satisfy the requirements of the design specification. In other words, if a proposed change satisfies the requirements of the additional documents, then the proposed change is a replacement in kind.
Common extensions to the design specification, illustrated in Figure 2, include:
- Operating envelopes: the operating envelope is the set of all combinations of parameters (e.g. temperature, pressure, flow) within which the equipment is certified to operate. When the operating point (i.e. a specific value of temperature, pressure, flow, etc.) is changed to a different operating point (i.e. a different specific value of temperature, pressure, flow, etc.) but still within the operating envelope, then such a change is considered a replacement in kind.
- Written procedures and business processes for operations: Any proposed change that is already documented in operating procedures, or related documents, is considered a replacement in kind.
- Written procedures and business processes for maintenance and repair: Any proposed change that is already documented in maintenance, repair or other procedures, or related documents, is considered a replacement in kind.
- Written training and qualification requirements: Any proposed change that is already documented as training requirements or people’s qualifications for certain tasks, is considered a replacement in kind.
- Schedules or schedule requirements: Any proposed change, that is within the bounds of an already documented schedule (e.g. March 23rd) or in schedule requirements (e.g. once each year), is considered a replacement in kind.
If a proposed change does not meet the requirements of any of these 5 design specification extensions, then the proposed change is not a replacement in kind.
Missing or Unavailable Design Specifications
A part failure in the plant calls for action. Most people can determine when a part, say a pump, is not working. However, not everyone can determine what the design specification for the pump is, how it’s documented, where those documents are stored, and, once retrieved, whether those documents are complete or even correct. Even in the absence of convenient access to the current design specification, and even without complete trust in any documented design specification, decisions still need to be made about whether a proposed change qualifies as an RIK. These decisions are made on a daily basis, and they tend to be justified based on 3 different assumptions:
- Grandfathering assumption: All equipment, and other process safety information (e.g. procedures) are assumed to be in compliance with the current design specifications. After all, prior to installing the equipment, or adopting the procedures, someone had to qualify it as being safe. In other words, all the existing equipment is grandfathered into the category of items which satisfy the design specification. Consequently, if a failed part is replaced with an identical part, then the replacement is considered in kind.
- Generic assumption: This is an extension of the grandfathering assumption. This assumes that the design specification is not vendor-specific. Therefore, failed parts can be replaced with parts from different manufacturers, provided that the physical, operational and maintenance parameters of the replacement part are the same as those of the failed part.
- Based on RAGAGEP and with no PSI impact: There is value in Recognized and Generally Accepted Good Engineering Practices, since this how the design specifications (original and current) were created in the first place. Neither the design specification nor the process safety information contains all details of all parts. When new situations arise (should we order a green one or a blue one?) which have no safety impact, and do not change the process safety information, then a properly qualified person may accept the item as a replacement in kind.
Lists of Replacement in Kind Examples
When a person encounters a potential replacement in kind situation, it would be helpful to have a list that indicates what is and isn’t an RIK in that circumstance. The more specific the RIK example, the more useful it is to the end user. For instance, information like ACME X100 valves can always be replaced by ACME X101Z valves would be helpful. However, a corollary to that statement is, the ACME X101Z valve satisfies the design specifications of the ACME X100 in all cases where the X100 is currently used. It may be true that the X101Z satisfies the X100 design specifications in some cases. But, all cases, everywhere? If there’s one situation, somewhere, where the X101Z is not a replacement for the X100, then the X101Z isn’t always a replacement for the X100.
So, attempting to come up with a universal RIK list, at this level of detail, isn’t practical since this list would be empty. However, it is possible to develop a site-specific RIK list at this level of detail, since a given part, like the X100, is only used in a few dozen contexts and those could all be analyzed beforehand.
Various authors [2-5] have provided lists of RIK examples. These examples are more general and are intended to be universal. I have taken all of these published universal RIK examples and reorganized them, using the model presented in Figure 2.