Heat Exchanger Inspection

7/21/2019 Heat Exchanger Inspection

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Concept for quality surveillance

exemplary at a shell-and-tube heat

exchanger

ACHEM ASIA 2013Joining in Chemical Apparatus and Plant Construction

May, 13th-16th, 2013, Beijing

BASF SE BASF Company Ltd.

Technical Inspection/Materials Engineering Quality Management/Materials Engineering

Dr. Rainer Eckrich Dr. Guang BinRao



Requirements of the "Internal Tightness"

of shell-and-tube heat exchangers

Possible impact of presumed leakage:

1) - No impact on "SHE" and environment

- Impact on product quality is not relevant

2) - No immediate impact on "SHE"

- Product contamination is relevant

3) - Immediate impact on "SHE"

- Product contamination is unacceptableOperator must define additional measurements

SHE: = Safety, Health and Environment

AchemAsia 2013 - Joining in Chemical Apparatus and Plant Construction



Requirements of tube-tube-sheet joints

(load criteria and tightness requirements)

-Design (minimum tube wallthickness)

-Manufacturing process

(rolling/expanding, welding,

number of layers)

- Type and scope of non-destructive testing

-Quality surveillance/

inspections during fabrication




Requirements of tube-tube-sheet joints

(load criteria and tightness requirements)

Load criteria A, B, C, D

Tightness requirement(impact of a presumed

leakage)1: No impact

2: No immediate impact

3: immediate impact

Example C3:

s = 2 mm; 2 layers

Including RT testing

In-fabrication inspection




Recommended weld preparation and

execution

Throat thickness shall be greater

than tube wall thickness (a ≥ t)

Deviating weld preparation

is possible but approval

is required

a

a




Implementing quality surveillance (1)

Measures before fabrication

Measures before fabrication starts

Advising the requisitioner/orderer

Inspection of the technicaldocumentation

Actions before beginning thetube-to-tube-sheet welding

“Mock-up” welding/procedurequalification

Monitoring of test welding/welders

Evaluation of the test samples AchemAsia 2013 - Joining in Chemical Apparatus and Plant Construction



Implementing quality surveillance (2)

Fabrication and testing

Measures during welding – in-

fabrication inspections

Weld preparation

Cleanliness

Executing the tube-to-tube-sheet

welding (skills/welding parameters)

Measures after welding – " final

inspection"

Visual inspection Manufacturer tests and inspections

(VT, PT, MT, LT)

RT inspection for heat exchangers

with tightness requirement "3"






Pores in tube-to-tubesheet welding

Result of radiographic test on tube-to-tube-sheet

joints




Inspection of shell-and-tube heat exchangers

Test equipment RT – “Back Radiation Technique

with Gammamat B3”

Test setup w ith isotope Ir 192

Additional inspection

Scope of inspection graduated by the

number of tubes and test result

(1st/2nd sample 100% or new)

Gammamat B3, 1 x 0.5 mm

source, activity max. 110 GBq Film C3, 10 x 12 cm, Pb 0.02 /

0.02, with holes




Improved Radiation-test-system (x-ray)

Anode grounded tubes, Warrikhoff, Berlin

Metal-ceramic tube MCTS 130 - 0.6

130 kV, 300 W, focal spot 0.6 mm

Emission angle 168 x 360°

Rod anode (Diameter 6 mm)

Transformer unit

Operating unit

kV cable

Film-based application / detector




Limits of application lr 192:

Dimensions tube-to-tubesheet joints

from 16 x 1.5 mm to 76 x 4 mm Carbon steel, high-alloy steel,

Ni-basis materials,

Tube-to-tubesheet joints with up to

15 mm projection

Oval tubes

Areas of application of x-ray tube:

From 8 mm inner tube diameter

Carbon steel, high-alloy steel,nickel and titanium

For customized design (projection

of tubes, material) - test piece

required

Limits of application

Gammamat B3 versus Grounded tube






Radiographic testing of the

tube-to-tube-sheet joints

1. With gamma ray source (Ir192)

Back-radiation technique

(d = 1 x 0.5 mm) or forward-radiation technique (d = 2 x 1 mm)

2. With x-ray tubes

(grounded anode tubes, d = 1mm )

back-radiation technique on filmbasis

3. With x-ray tube (grounded anode

tube) – back-radiation with CdTe

detector

Detectabili ty of irregularities

D e t e c t a b l e s

i z e o f f l a w ( m

m

)

0.5

1.0

1. Ir192

2. Rod anode on film basis

3. Rod anode with detector

0.3

0.2

Detectabili ty of irregularit ies

Comparison of test systems

mm




RT scope of inspection of the tube-to-tube-

sheet joints as per table 6.3.1, BASF E-S-

MC 331

RT scope of inspection and evaluation criteria

(E-S-MC331)

Evaluation criteria as per table 6.3.2.1

!Evaluation and acceptance

criteria do not depend on

test-system

!




Improved RT test system

Comparison of tests systems

Ir192 + film Rod anode + film Rod anode + detector

85 GBq, 1 x 0.5, film C3,

2 x 0.02 Pb film

tB

= 1 min

130 kV, 0.5 mA, film C3,

1 mm Sn pre-filter, 2 x 0.02 Pb

tB = 0.5 min

75 kV, 0.5 mA,

tB = 0.5 min

High pass filter

0.8 mm

0.5 mm

0.3 mm





x-ray film / detector pictures

Tube dimension Ø 25 x 2 mm, exposure data: 80 kV/ 0.5 mA / 30 sec

Detector picture

Pore

and

tungsten

inclusion

X-ray film





Tube dimension Ø 25 x 2 mm

X-ray film PT Inspection Detector picture




Comparison of RT-test systems

Summary

Isotope Ir192 –

film-based

X-ray tube –

film-based

X-ray tube -

detector-based

Advantage:

• large scope of object

• easy to use

Disadvantage:

• permanent source ofradiation

• disintegration of theisotope

• reduced detectability of

details

Advantage:

• high detectability of details

• fixed recording parameters

• simple transport

Disadvantage:

• lower scope of object

Advantage:

• see x-ray tubes

• lower radiation exposure

• immediate evaluationpossible

Disadvantage:

• sensitive technology

• high investment cost




Classif ication of shell-and-tube heat exchangers

purchased in 2012

Q u a n t i t y

Classification

Total: 342




Summary and Outlook

Number of leakages in shell-and-tube heat exchangers due to

fabrication-related errors substantially reduced

Wide acceptance of this BASF standard in projects and while procuring

heat-exchangers

Procedure successfully implemented in Europe, Asia and in the US

Inclusion of heat exchanger tubes in this quality surveillance concept

Application of “Risk based quality assurance (RisQ)” to further welded

constructions and standards




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Heat Exchanger Inspection

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