Chapter 1: In-Service Inspection

1. Introduction
This manual has been formulated to serve as a minimum reference base of ONE-M GROUP’s Inspection personnel to carry out plant In-Service inspection including turnaround as required by statutory body i.e Department of Occupational Safety and Health (DOSH)  Malaysia and plant owner.

The applicable Malaysian Laws and Regulations are;

a.     Factories and Machinery Act 1967 (Subsequent Amendments)

b.    Petroleum (Safety Measure) Act. 1984

1.1 Objective of In-Service Inspection

The purpose of In-Service inspection on items such as pressure vessels, heat exchangers, etc, are to intercept failure while it still in its initial stage, and to be able to plan and perform necessary remedial works at proper interval. Also, by carrying out in-service inspection, unnecessary events may be avoided from occurring. Thus, a well planned in-service inspection could:

a.     Prevent accidents that could cause undue risk to the personnel working at or near the plant.

b.    Prevent accidents that could cause severe material damage and consequently substantial economic losses.

c.     Prevent accidents that could cause undue risk of pollution to the environment.

d.    Prevent undue stop pages in the production of the plant.

If during in-serve inspection is carried out, some abnormalities are found on certain equipment; further investigation shall be called for, such as, the use of non-destructive testing methods.

1.2 Inspection Personnel (Inspector)

Inspector for the purpose of this inspection shall have tertiary education and have at least 4 years working experience in performing plant inspection and testing and/or repair on pressure vessels or other DOSH registered equipment. Inspector shall undergo mock up test as and when required by Client to proof its ability.  Inspector shall also confirm fit physically by medical practitioner and have to undergo annual check up to ensure fitness. Other requirements such as vision, color blindness, hearing etc shall confirm to standard health requirements set certification body such as API, PCN/CSWIP with API 510.

1.3 Inspection tools

For the purpose of the manual the following inspection tools are to be furnished to the Inspectors to ensure effective and accurate inspection result to be submitted to Client or DOSH;

Essential;

1.     Torch light

To provide adequate lighting for general visual inspection. To check the longitudinal straightness of shell, to detect buckle and to detect shell surface unevenness, dents, corrosion, pit, gauge, groove … etc.

2.     Scrapper

To remove scale/rust if any to have better view of the examined area.  Rag And Steel brush must be available for the same purpose.

3.     Straight Edge Ruler (6”)

To estimate thickness of plates /pipe size/nozzle size and flatness of the surface, straightness of nozzle.

4.     Welding Gauge

To measure lost in weld cap or lost in thickness at HAZ, groove depth hi-low in weld.      

5.     Magnification Hand Len

To have close-up view of surface defects especially fissure crack or to identify surface pits/marks.

For Further Measurement or Investigation

Optional;

6.     Pit Gauge

To measure accurately the pit depth.

7.     Camera

To record damages/failure or any non-compliances and as evidence for illustration, discussion, reporting, etc.

8.     Mirror/Boroscope

To inspect internal area of bends in nozzle inlet/outlet from vessel.

9.     Non-Destructive Testing: DPT/MPI

To detect surface crack if there is any sign of damage/impact on nozzle or vessel shell that may cause surface crack.

10.  Ultrasonic Testing

To check remaining wall thickness at specific location (eg. pit-hole, groove, etc) from opposite side. To detect and scan for defect at area which is suspected of having defect/internal crack.

1.4  Basic Principles of In-service Inspection

Described below are few basic principles that are to be implemented in an in-service inspection program

Types of Inspection

a.     General visual inspection

b.    Detail inspection

a.     General visual inspection:

Usually covers items such as header, shell, manhole, nozzle, coating, flange, gauge/meter, bolt-nut, etc.

Requiring only portable inspection instrument and no interruption on the part of the production.

b.    Detail inspection

Is a more thorough inspection by carrying out extra examination and testing on selected critical areas. Additional examination and testing such as NDT methods may be required in the inspection. Frequency and extent of inspection shall depend on the criticality of the items to be inspected and in case DOSH registered equipments its depend on DOSH regulation set force. A more critical parts or items require higher frequency of inspection. Therefore, the items or equipment to be inspected shall be categorized according to their criticality. For example, general visual inspection is to be carried out at an interval of 3 to 36 months depending on the criticality of their equipment. As for detail inspection, it is usually carried out annually or at a lower frequency than general visual inspection.

1.5  Inspection Reviews

An inspection review is carried out to suggest that an Inspection Category given at the detail inspection shall be changed. It involves carrying out such on-stream inspection as may be possible or necessary and examining other relevant data which may be available, eg from corrosion coupon, wastage rates, metal contents of effluent streams, etc. The pressure vessels, heat exchangers and boiler shall be subjected to an inspection review when:

i)      Significant changes occur in the places and services conditions of the equipment that may affect its deterioration rate in whole or in part.

ii)     An abnormal incident occurs, which has affected the safety operation of the equipment.

iii)    Any changes occur since the detailed inspection that may lead to a possible shortening of the interval allowed elapsing before the next detail inspection.

iv)    There are changes in the inspection results, where reduction of inspection interval may be necessary.

v)     There are changes in the inspection results, where reduction of interval between inspections may be necessary.

1.6  Selection of Inspection Category

The selection of the Inspection Category for the pressure vessels boilers and heat-exchangers can be considered with the following factors:-

(i)     The age of the item and length of time of the commissioning.

(ii)    Severity of the service duty and the consequences of the CO2, wet H2S environment.

(iii)   The standard of design, material and construction of item.

(iv)  Previous history of the type of equipment or items. (Reviews all the necessary technical papers related to the equipment).

(v)   The optimum utilization of the equipment.

1.7  Typical In-Service Instruction of a Petrochemical Plant on the Unfired Pressure Vessel (UPV)

1.7.1     Introduction

This Instruction outline the statutory requirements in the inspection of unfired pressure vessels in accordance to DOSH regulation currently set force. These inspection requirements are applicable to new and operating unfired pressure vessels.

1.7.2.    New Pressure Vessels

Detailed drawings, calculations, details of instrumentation and welding and testing procedures are to be submitted to DOSH for approval. DOSH will review these documents, stamp their approval and return it for record. DOSH has to be notified of all welder qualification tests, procedure qualification test, NDT and hydrostatic pressure test. DOSH Inspectors will witness these tests and indicate their acceptance. An application for permission to operate the pressure vessels at certain safe working pressure has to be submitted to DOSH after satisfactory completion of all required test. DOSH will issue a “Certificate of Fitness” valid for fifteen months from the date of issue. This certificate will contain the DOSH registration number (PMT…………) and this registration number has to be stamped on the nameplate of pressure vessels. Pressure vessels fabricated outside Malaysia have to be re-hydrotested at the plant for witnessing by DOSH. Certification by Inspecting Authority (as in the Fourth Schedule, F & M Act.) is necessary.

1.7.3     Operating Pressure Vessels

Internal visual examination is required to extend the certificate of Fitness. However , DOSH will consider extension of the Certificate of Fitness for a period of thirty six months from the data of original issue on external visual inspection, thickness monitoring and previous inspection findings. Hence all unfired pressure vessels are subjected to periodical inspection. All modification to be performed on the operating pressure vessels shall follow the same procedures as the new pressure vessels. To ensure that the operating pressure vessels are fit-for-service at all times, it is prudent to inspect them periodically according to technical  requirements and procedures as described in In-service Inspection Manual. Normally on External Visual Inspection of at test once a year is sufficient, frequency may increase on problem-vessels. A report is to be made on each inspection.

1.7.4     Inspection Manual

It is necessary to develop on Inspection Manual on Unfired Pressure Vessels with detailed instruction and Procedures for inspection, testing, reporting, recording and repairs.The area of coverage shall include and not limit to:-

i.    Internal Visual Inspection

ii.     External Visual Inspection

iii.    Overhaul, Inspection and Testing of PSV

iv.    Thickness Gauging Monitoring Program

v.     Turnaround and shutdown Inspection

The Inspection Manual shall include guidelines for the Evaluation and Analysis of all inspection findings and test results.

1.7.5     Internal Inspection

Internal visual inspection of all columns, drums reactors, heat exchangers, fired heaters, filters etc is to be performed at least once in three years and as instructed by DOSH. Internal of columns, drums, reactors and filters are to be checked for corrosion, discoloration, scales, integrity of attachment welds and condition of screens, wire mesh or filter cartridge. In addition, shell and tube exchanger visual inspections are to include checked of tube sheet welds and cleanliness of tubes. Ultrasonic thickness measurement of tube of fired heaters is to be performed if visual inspection reveals suspect areas. A few plugs are to be opened on air-cooled heat exchanger to inspect the condition of the inside of the headers. Flange faces of all connections that have been opened are to be installed reassembly. Individual reports are to be generated for each major equipment inspected. Further details are to be included in the Inspection Manual of Unfired Pressure Vessels.

1.7.6     Thickness Gauging Monitoring Program

Thickness gauging is part of the overall plant erosion and corrosion monitoring program. The thickness of pressure vessels are periodically checked to determined the predicted design life of the vessels as well as to identify the areas which may have deteriorated due to erosion and accelerated local corrosion. Normally twice thickness gauging per year is sufficient, frequency may increase at highly corroded & eroded area. The details of procedures, equipment, tools, reporting, frequency and recording are to be stipulated in the Inspection Manual of Pressure Vessels.

1.7.7     Inspection of Pressure Safety Valves (PSV)

All the PSV’s are to be visually inspected at least once a year are also they need to be dismantled, cleaned, overhauled, repaired and tested every three-year. The detailed procedures and requirements are described in the In-Service Inspection Manual of Pressure Vessels. However if there is any doubt on the integrity of any of the PSV, twice per year of visual inspection may be necessary.

1.7.8     Evaluation and Analysis

The In-Service Inspection Manual shall include the guidelines on the Evaluation and analysis of all the inspection findings and test results. An appropriate Evaluation and Analysis will provide a better picture on the actual condition and integrity of the Pressure Vessels. Trend analysis and Statistical Analysis may be included.

1.7.9     Other Statutory Requirement

Beside the statutory requirements on the inspection of unfired pressure vessels other relevant statutory requirements include:

i.    Reporting

ii.     Power of DOSH Inspector to carry out Investigation and Enquiries.

iii.    Notice to inform DOSH on sale, hire, transfer, alteration of the pressure vessels.

Inspection Section personnel shall observe these statutory requirements.

1.7.10   Records and Documentation

The records and inspection reports are to be kept properly according to the requirements of inspection Manual of Pressure Vessels. It is necessary to keep a record of all inspection results of each unfired pressure vessels, from the initial inspection to the latest inspection, so that comparison and analysis can be made from loss or damage, however they shall remain easily accessible or retrievable whenever necessary.

1.7.11   Corrective Action and Internal Audit

All unfired pressure vessels are to comply with strict statutory requirements, especially in relation to any hot-work repair on permanent parts of the vessels that need the approval of DOSH Inspector. Hence, Inspection Section personnel need to follow-up all the corrective Action on hot-work repair with specific attention on the statutory requirements. However, in the case of non-hot work matters such as painting, coating, insulation, cleaning, replacement of gauges etc which are to be executed by Maintenance or Operation personnel, then Corrective Action of such nature may not be the responsibility of Inspection Section. All Corrective Actions will remain outstanding until they are completed satisfactory. Outstanding Corrective Actions may lead to the situation of the vessels being classified as not fit for operation; hence all outstanding corrective actions after the due date shall be submitted to the Section Manager and Plant Manager immediately for further consideration. The head of the Section may carry out on Internal Audit on the inspection work and documentation related to the unfired pressure vessels. The purpose of the Internal Audit is to verify that the work done and documentation are in compliance with statutory and specified requirements; the findings and observations are useful for future improvement.

1.8  A Typical Inspection & Testing Instruction on Pressure Safety Valves

1.8.1     Introduction

This Instruction stipulates the inspection and test requirements of Pressure Safety Valves. Pressure Safety Valves (PSV) are vital to the plant safeguards system and are to be periodically tested to ensure proper function. Testing of PSV’s is performed once a year every three years as a minimum. In addition, if the Operations Department experiences problems/malfunction of any PSV, they may arrange with Maintenance Department for repair/readjustment of the scheduled test.

1.8.2     Procedure

Maintenance Department is responsible for planning and scheduling the testing of PSV’s. Test schedule will be forwarded to the Inspection Section. The Inspection Section will provide the set pressure requirement for each of the PSV’s from the Test Certificates on record. The test procedure shall follow in “PSV’ Inspection, overhaul and Testing Procedure”. Visual Inspection is to be performed once/year (See PSV Visual Inspection Form as enclosed). Inspection Section will witness the testing of PSV’s to procedure, the setting is within acceptable limits and to perform other checks as outlined in the procedure. Setting to be monitored and controlled by Inspection Section. PSV-seals are maintained and controlled by the Inspection Section. The inspector witnessing the tests will affix the seals to PSV’s after satisfactory completion of all required tests. Sealing of the PSV’s is to be witnessed by operation and maintenance department representative.

1.8.3     Documentation

Test Certificates are to be completed and certified by the Inspectors in conjunction with the tester and maintenance supervisor. The Inspection Section for record retains the completed test certificates. All certificates shall be kept in file with proper indexing for trace ability and prevention from damage or loss.

1.8.4     Internal Audit

The PSV test procedure, test reports and certificates are too subject to Internal Audit. The purpose of Internal Audit is to verify whether documentation and procedure are in compliance with the written requirements.