Dipresentasikan pada seminar Korosi Metalurgy & Material Week 2011 :Permasalahan dan Penanggulangan Korosi pada Industri Migas di Indonesia.Jakarta (Patra Jasa Office Tower), 13 14 Desember 2011

HOW TO HANDLE IT a sharing experience from PHEONWJ

Shared by : Ifan Rifandi

Corrosion Under Insulation, How to handled it, a sharing experience from PHEONWJ

Corrosion under insulation (CUI) is the corrosion of piping and vessels that occurs beneath insulation as a result of water/ moisture penetration.

CUI is hidden under the insulation therefore CUI tends to remain undetected until the insulation is removed for inspection or when leaks occur.

CUI Incident Lesson learnt from Dow Chemical Plant

On March 13, 2008, at a Dows LHC plant, 8 schedule20, carbon steel hydrocarbon line failed. The piping was a30 year old.The material in the line was non-corrosive hydrocarboncracked gas (40% ethylene). Due to the regenerationservice, the piping alternates between three differentconditions, and the location of failure was where operatingtemperatures cause frequent or continuous condensationand re-evaporation of atmospheric moisture. (courtesy of DowChemical)

Regeneration condition (4 bar, 220 C)On stream time: 20 days (30 bar, -17 C)Regeneration time: 24 hrs(220 C)Standby: 19 days (ambient temperature)

Corrosion Under Insulation, How to handled it, a sharing experience from PHEONWJ

Equipment is insulated for any of the following reasons:1. Heat conservation and/or freeze protection2. Condensation control3. Sound control4. Personnel protection5. Fire protection.

Carbon steel corrodes, not because it is insulated, but because it is contacted by aerated water/ moistureThree basic ingredients must present to form CUI : Moisture Warm temperatures (CS = 4C (25F) up to 175C (350F) or (SS = 50C (25F) up to 175C (350F) Corrodent contaminant The two primary moisture/ water sources involved in CUI of carbon steel are : Infiltration from external source Condensation

Corrosion Under Insulation, How to handled it, a sharing experience from PHEONWJ

Contaminant in insulation system can be classed in two primary classes. Contaminant external to the insulation materials Contaminant leached from the insulation material

API 570 specifies :

Susceptible Temperature Ranges API 570 Piping Inspection Code, Section 5.3.3.1 e, f & h:e. Carbon steel piping systems, including those insulated for personnel

protection, operating between 25F250F (4C120C). CUI is particularly aggressive where operating temperatures cause frequent or continuous condensation and re-evaporation of atmospheric moisture.

f. Carbon steel piping systems that normally operate in-service above 250F (120C) but are in intermittent service.

h. Austenitic stainless steel piping systems operating between 150F400F (65C204C). (These systems are susceptible to chloride stress corrosion

cracking.)

Corrosion Under Insulation, How to handled it, a sharing experience from PHEONWJ

Suspect Areas API 570 Piping Inspection Code, Section 5.3.3.2The areas of piping systems listed in 5.3.3.1 may have specific locations within them that are more susceptible to CUI, including the following:a. All penetrations or breaches in the insulation jacketing systems, such as: 1) Deadlegs

(vents, drains, and other similar items), 2) Pipe hangers and other supports, 3) Valves and fittings (irregular insulation surfaces), 4) Bolted-on pipe shoes and 5) Steam tracer tubing penetrations.

b. Termination of insulation at flanges and other piping components.c. Damaged or missing insulation jacketing.d. Insulation jacketing seams located on the top of horizontal piping or improperly lapped or

sealed insulation jacketing.e. Termination of insulation in a vertical pipe.f. Caulking that has hardened, has separated, or is missing.g. Bulges or staining of the insulation or jacketing system or missing bands. (Bulges may

indicate corrosion product buildup.)h. Low points in piping systems that have a known breach in the insulation system, including

low points in long unsupported piping runs.i. Carbon or low-alloy steel flanges, bolting, and other components under insulation in high-

alloy piping systems.j. Locations where insulation plugs have been removed to permit piping thickness

measurements on insulated piping should receive particular attention. These plugs should be promptly replaced and sealed. Several types of removable plugs are commercially available that permit inspection and identification of inspection points for future reference.

Corrosion Under Insulation, How to handled it, a sharing experience from PHEONWJ

Corrosion Under Insulation, How to handled it, a sharing experience from PHEONWJ

How to handle it

1. RBI approach Risk study/ identification Risk Mapping Inspection prioritization Etc.

2. Process requirement approach Aging facilities Re-engineering study of existing & future process requirement Issue recommendation Prepare facility change permit (FCP)

Corrosion Under Insulation, How to handled it, a sharing experience from PHEONWJ

Define ProgramStation Name - CUI Risk Reduction program

Socialization(site owner, executor, inspection, HSE, etc.)

Engineering Study & Recommendation

MOC Documention (FCP)

Execution

Prepare Work pack

Insulated pipe inspection without insulation removal

Insulated pipe inspection without insulation removal

Work package

1. Engineering Recommendation2. Material Selection (Hot & Anti sweat Insulation, Cage material,

Coating material, etc.)3. Cage & Insulation Installation Design4. Application Procedure5. Potential Hazard / Risk Assessment6. Data Sheet

Work package

Material Selection (Insulation Specification)

Insulationmaterial

Compressive strength range [kPa (lb/in2)]

Other significant properties Comments

Calcium silicate 410 1 700 (60 250)@ 5% deformation

Able to absorb up to 400 times its own weight of water.High-pH extracts, but aggressive to steel when wet.

Suitable only for plant operating consistently at high temperatures > 100C (212F).

Glass fibre 3,4 17 (0,5 2,4)@ 10% deformation

Able to transmit moisture.Chemically inert.

Will support corrosion on unprotected steel.

Mineral fibree.g. Rockwool

69 - 410 (10 60)@ 5% deformation

Non water repellent grades able to transmit (wick) moisture.Chemically inert.

Even water-repellent grades support corrosion on unprotected steel.

Organic foams- Polyurethane- Polyisocyanurate- Phenolic

69 - 480 (10 70)@ 10% deformation

(*See footnote)

Able to absorb and transmit water, particularly when damaged.Low pH and halide extracts possible at elevated temperatures.

Not recommended for equipment operating at temperatures above ambient.

Cellular glasse.g. foam glass

340 1 600 (50 230) Non absorbent provided it remains intact.May release acidic species (CO2, H2S) if cells are broken.

Stable over a wide operating temperature range.High compressive strength gives good integrity.

Flexible elastomeric foams

280 (40)@ 10% deformation

100% closed cell.Low water absorption (about 1%).Non aggressive to steel.

Upper temperature limit 105 to 150C (220 to 300F), depending upon specific product. Need to allow for circumferential thermal expansion.

*Note: organic foams are anisotropic with the compressive strength parallel to the foam, about twice that perpendicular to it.

Cellular Glass

b. Anti sweat insulation material Safety / health friendly Chemically inert Physically robust Easy to be applied Market availability

Work package

Calcium Silicate

a. Hot insulation material Safety / health friendly Chemically inert Physically robust Easy to be applied Market availability

c. Coating material Safety / health friendly Anti corrosion coating Easy to be applied Market availability

Can be applied without plant S/D

Work package

Epoxy Phenolic (< 150 oC)

Epoxy Novolac (< 250 oC) Inorganic Zinc + Silicon-Aluminium (

d. Cage material

Work package

Corrosion resistant Physically robust Easy to be applied Market availability

304 SS perforated plate

Work package

Application Procedure Insulation removal procedure New insulation installation procedure Emergency/ temporary piping repair procedure Coating application procedure Cage installation procedure Etc.

Risk AssessmentData sheet & MSDS material

PHEONWJ Sharing - CUI risk reduction program

PHEONWJ Sharing - CUI risk reduction program

PHEONWJ Sharing - CUI risk reduction program

PHEONWJ Sharing - CUI risk reduction program

Survey (Validation, Cost Estimation, BOM)

Execution

Provision Material (Coating, Insulation, Cage,

Emergency Repair, Etc.)

Assign SPA & appoint Executor Party

Fabrication

Scaffolding Installation& Insulation Removal

WT Inspection & temporary repair (if any)

Surface Preparation & Coating Application

Re-InsulationCage Installation

Final Report

PHEONWJ Sharing - CUI risk reduction program

PHEONWJ Sharing - CUI risk reduction program

PHEONWJ Sharing - CUI risk reduction program

Insulated pipe inspection without insulation removal

1. Infrared Thermal Gram2. Profile radiography3. Real Time Radiography or Lixi4. Neutron Backscatter5. Ultrasonic Teletest6. Acoustic Emission7. Pulsed Eddy Current (Incotest)

Infrared detect damp spot in the insulation, because usually temperature difference between dry insulation and wet insulation are detectable.Corrosion is possible occurred beneath the wet insulation.

Insulated pipe inspection without insulation removal

Exposures is done in a small section of the pipe. A comparator blocksuch as a Ricki T is used to calculate the blowout factor for the exposure inorder to calculate the remaining wall thickness of the pipe.

Profile radiography is an effective evaluation method, but radiation safety can be a real concern that nobody can work within the area while the inspection is underway. This can result in downtime and personnel scheduling conflicts.

Insulated pipe inspection without insulation removal

The real time device has a source and image intensifier/ detector connected to a C-arm. Fluoroscopy provides a clear view of pipe outside diameter through the insulation, producing silhouette of the pipe outside diameter on a TV type monitor.

There are two type device, one using a X-ray source and another using a radioactive source. Each has its own advantage and disadvantage, however X-ray type deliver better resolution.

Insulated pipe inspection without insulation removal

The Neutron Backscatter Technique works due to the principles of the interaction of neutrons with matter. The radioactive source emits fast neutrons with high energies which are difficult to detect. These fast neutrons interact with matter to become slow or thermal neutrons. Thermal neutrons are most likely to interact with atoms of a similar size to the neutron itself. Hydrogen is the atom closest in size and mass to the neutron and therefore accounts for the majority of the collisions that reduce the fast neutrons to thermal neutrons. When a fast neutron collides with a hydrogen atom it releases energy and becomes a slow or thermal neutron. The thermal neutrons are scattered in all directions but have a short travel path. Some of these thermal neutrons are scattered back towards the scanning head and these are the neutrons counted by the detector

Insulated pipe inspection without insulation removal

Ultrasonic Teletest (known as the Teletest Focus) is developed by TWI. It is used Guided Wave Ultrasonic (GWU) technology.These inspections are carried out using multi-mode (flexural and torsional)wave focusing approach. This technique provides 100% inspection coverage and has the ability to inspect inaccessible areas such as clamps, pipe elbow and cased or buried pipes.Originally developed for the inspection of corrosion under insulation, the Teletest Focus is suited for application to pipelines and process pipe work, including road crossings, bridge piers and hardly accessible pipe work generally.

Insulated pipe inspection without insulation removal

Acoustic emission monitoring is the analysis of the ultrasonic waves generatedby dynamic events, such as deformation and cracking, occurring in thematerial under investigation. Thus, stress corrosion cracking, hydrogenembrittlement and corrosion fatigue can be detected. However, acousticemission cannot indicate the size of a defect, only whether a defect is growingor not.

A typical AE system setup.

Insulated pipe inspection without insulation removal

Incotest is Pulsed Eddy Current licensed by Shell Global Solutions. A currentpulse is sent through a coil. When the current is interrupted, eddy currents aregenerated in the material, which will decay in time. Measuring the rate ofdecay of the eddy currents will determine the wall thickness. High wallthickness will result in a slower decay. The description of the equipment isshown in Attachment Q.