Management of change (MOC): process, steps and engineering change

What is management of change?

Management of change is a formal procedure for proposing, assessing, approving, implementing and closing out changes. It is one of the core elements of process safety management, alongside process safety information, process hazard analysis, operating procedures, mechanical integrity and pre-startup safety review.

The goal is simple: no change goes into service without someone competent asking what could go wrong, deciding it is acceptable, and making sure the drawings, procedures and people are updated to match.

What counts as a change?

A replacement in kind (an identical part, or one that meets the same design specification) is not a change and does not need MOC. Deciding what is and is not "in kind" is itself part of a good MOC procedure.

The MOC process step by step

1. 01
   Raise the request

   Describe the change, the reason, the technical basis and the systems affected.

2. 02
   Classify it

   Permanent, temporary (with an expiry date) or emergency; minor or major. The class sets how deep the review goes.

3. 03
   Assess the hazards

   A checklist, what-if, HAZID or HAZOP as the change demands, covering process safety, occupational safety, environment and operability.

4. 04
   Review by the disciplines

   Process, mechanical, electrical, instrument, operations and safety review the change and set conditions.

5. 05
   Approve

   Authorised approvers sign off, at the level the classification requires.

6. 06
   Implement

   The change is made under the normal work permit and quality controls.

7. 07
   Update documents

   P&IDs, process safety information, datasheets, procedures, alarm and trip schedules and maintenance plans are updated.

8. 08
   Train and communicate

   Operators and maintenance staff affected by the change are informed and trained before it is used.

9. 09
   Pre-startup safety review

   For significant changes, a PSSR checks construction, procedures, training and PHA actions are complete before start-up.

10. 10
    Close out

    All actions are closed, documents issued, and temporary changes removed or made permanent by their expiry date.

OSHA process safety management requirements

In the US, OSHA's process safety management standard (29 CFR 1910.119) requires employers covered by it to have written MOC procedures for changes to process chemicals, technology, equipment, procedures and facilities that affect a covered process (paragraph l). The procedures must address:

• The technical basis for the change.
• The impact of the change on safety and health.
• Modifications to operating procedures.
• The time period for the change.
• Authorisation requirements for the change.

Employees affected by the change must be informed and trained before start-up, and process safety information and procedures must be updated. Paragraph (i) requires a pre-startup safety review for new facilities and for modified facilities when the change is significant enough to require a change in the process safety information. Similar requirements exist elsewhere, for example in the EU Seveso III directive and the UK COMAH regulations.

Temporary and emergency changes

Temporary changes are the weak spot of many MOC systems: a temporary clamp or bypass that is still there years later, never reviewed as permanent. A temporary MOC carries an expiry date, an owner and a removal plan, and is tracked until it is removed or converted into a permanent change through the full process.

Emergency changes, made to keep the plant safe when there is no time for the full review, get a minimum review at the time and the full review immediately afterwards.

Engineering change on capital projects

During design and construction, the same idea runs through different names: technical queries (TQs), site queries, field change requests, design change notices and engineering change requests. Each change ends up as a drawing revision, and each revision can change tags that already have work done against them.

• A signed inspection record may have been made against the old revision and need repeating.
• A punch item may be resolved by the change, or a new one may be needed.
• A test pack may need its line list, limits or spades updated, and possibly a re-test.
• A commissioning procedure may have steps that no longer match the P&ID.

Finding all of that by comparing revisions by eye is slow and things get missed. The impact of each revision has to be traced tag by tag before anyone signs against the old drawing. See how to read a P&ID.

Good MOC practice

• Make it easy to raise a change, so people do not work around the system.
• Scale the review to the risk: a simple checklist for minor changes, a HAZOP for major ones.
• Link each MOC to the documents and tags it affects, so updates are not forgotten.
• Track temporary changes to their expiry dates.
• Review open MOCs regularly and audit closed ones for quality.