5.3 Plant Maintenance: MOM Statutory Inspections (Singapore)

This post will cover only maintenance aspects of MOM Statutory inspections but not design and construction.

A little story about MOM and its jurisdiction control
MOM is the Ministry of Manpower in Singapore. Under this ministry, a Workplace Safety and Health department takes care of all industrial health, safety, environment related issues.

Pressure vessels, boilers, steam related equipment and more all fall under jurisdiction control. They pay attention to equipment carrying steam, air and refrigerant. Nothing else.

The lack of jurisdiction over equipment carrying other hazardous fluids probably because those are usually taken care of by ASME or CE inspections where most equipment makers needs to comply to.

We also know that steam, air and refrigerant is the most common utilities fluid used in industrial installations since the era of industrialization in 1900s. The rule book was passed down from British Law and developed then on, and little probably changed.

Inspection Intervals
These vessels are required to be inspected during fabrication by an accredited Authorized Examiner(AE) This is similar to the Authorized Inspector(AI) in ASME context. What needs to be done here will not be explained here, as we are more focused on maintenance and operations.

How about during Operations? What requires inspection on an interval basis by an AE.

• Air/Steam Receivers (PV & exchangers)
• Piping
• Steam equipment
• Safety valves connected to the above devices

Interval and details of inspection
Steam Boilers fired and unfired - 1 year

Steam/Air receivers - 2 year

Refrigerant receivers - During Fabrication and After Repairs
Piping - During Fabrication and After Repairs (For MP and HP steam systems)
Hydrotesting - After repairs or every 10 year

Thickness Measurement - 10 year
Safety valves - Calibrated during the inspection interval

Corporate Level Assessment
New initiatives: Corporate Level Assessment. What is it?
With this intitiative, delayed Statutory inspection intervals could be applied by plant owner. However this is subjected to approval after submission of the relevant maintenance procedures, inspection data and reports, audit reports and etc,

This initiative is designed to be somewhat ambiguous this is so that approval can be made on a case by case basis. However rest assured safety related corruption cases will be weeded out due to high level of interviews on MOM Authorized Examiners and corporations during the submissions.

Under this initiative boilers can be granted extension of 2 years and pressure vessels 5 years. Depending on condition of equipment and documentation submitted. Requiremets are as such

- Competent Person (CP) to be engaged to scrutinize the CLA reports to be submitted ( this is on top of AE and cannot be the same person)

- Yearly Internal Audit to ensure that the below are in place to be done internally. 

- 2 Yearly Audit by an External Agency. (Similar to the internal audit, except that its called a Technical Audit. Requirements for the audit is a long list of reports, as you can see below)

- All related Visual Inspections and NDT shall be carried out by an SAC accredited Inspection Body(IB)
- All related Calibrations shall be carried out by an SAC accredited laboratory

- Scheme For Guaranteed Safe Use (SGSU) to be developed, this is basically the equipment inspection plan, company safety procedure, plant process description, brief maintenance and operation history of equipment to be captured, equipment datasheets & drawings, organization chart of key parties, 

- Produce to auditors yearly eqpt remaining life calc, BFW pump condition monitoring logs, BFW treatment logs, steam blowdown logs, PSV test summary and certs, documents pertaining to RBI if any, past CLA audit reports if any, past CP report if any.

- The above requirement may vary, depending on what is found in the approved SGSU submitted and approved. So do submit only what is within your means and resources. Just follow the SGSU and you will be fine, if not you may be fined or removed from CLA Scheme!

Repairs

All Repairs needs to be informed by writing/emailing to MOM directly for approval by commissioner before appointing an AE for the endorsement of repair. 

Method statement of fabrication, inspection and testing plans will need to be submitted for endorsement by AE and review by MOM. Repair requirements per API 510, NBIC or PCC-2 has so far been accepted, mostly subjective to decision of the AE. 

3.2 Valve Spec & Purchase

What Are Valve Specifications?

Similar to piping specification, but provides you the guide to what those valve commodity codes on the piping specification means.

Typical information includes:
1) Commodity code
 Commodity codes are usually a long string of text for example the below I have seen:

*VOEACCM

*VAACE6PM

*CVV1137YY

These codes is how Company or Contractor label their valves in a systematic manner based on the specifications below.

2) Type of service
The service fluid the valve is recommended for.

3) Materials of construction

 Material of construction of the body, stem, handwheel, disc, seat. 

Type of body constructions for example forged, casted, machined, etc.. (Body commonly casted)

3.1)Type of Trim
This is the material specification of the disc and seat. Read API 600/602 for a list of trims typically carried by vendors and their applications. They range from a number from 1 to 12 and this numbering is not in order of anything.

Trims can come in hard or soft material. Where Hard here refers to hard facing material such as stellite and martensite stainless steels (400 series) and soft refers to the usual 316. There are other classes of trims non-API for example resilient soft seats used in harsh chemical service in typical resistant materials such as PTFE, PEEK, VITON and many more, theses resilient soft seats are usually much susceptible to damages and would require increased frequency and cost of maintenance.

3.2 ) Packing construction

*Packing compression type: with or without Bellville springs 

Teflon or other Polymer packing

Steel wire reinforced graphite yarn packing 

Or a mixture of graphite yarns with pure graphite rings (Harsh applications)

4) Type of Valve construction for eg.
Ball - 3 piece bolted, 2 piece screwed
Globe/Gate - bolted bonnet, screwed bonnet, welded bonnet, pressure seal
Butterfly - wafer type, lug type
Check - Piston, swing disc, lift disc, butterfly double disc, hoerbiger type

5) Flow Pattern
High/Low CV
Full bore / Reduced bore.
2 way, 3 way, 4 way flow.

6) Valve Testing and Inspection
Most common testing and inspection standards for new and repair of valves will comply to API 598.
Refer to it for exactly what needs to be tested and inspected to verify that a valve is fit for service. It fulfils the basic requirement to ensure valves qualities.

Purchasing Issues

Some thing you might ponder about during purchases:

Why are certain brands so significantly cheap / expensive? 

Let us break down a valve into its individual components to analyze. When you breakdown to this level you would realize each valve is intricate when you perform the installation and maintenance. 

However from an inexperienced purchaser/piping designer point of view, they will consider a valve as "it's only a valve." without realizing valves are part of a major problem in a plant should it be of inferior quality, Potential problems we might face will be mentioned in  Section 3.7 Valve Repairs.

Potential areas observed that manufacturers saves on that are less investigated by purchasers/piping designers:

* Packing design and material (Potentially results in low MTBF, frequent leaks)

* Body material (Composition of ingot material from inferior source not meeting composition req'd)

* Casting method (Casting method/flow plays great importance in strength of material)

* Quality Control (Despite documentation, hidden lapses and doctored inspections would still be present from some overseas manufacturers especially in China/India where QC seems haphazardly done. Nevertheless, I have still seen quality products from China and India, of course at a higher price. So nationality of these valves shouldn't be stereotyped, but rather the quality control process and how the purchaser would like to manage these issues should these lower cost destinations needs to be specified.

Point at the end of the day... You usually pay for what you get.