HDPE as a New Alternative Material for Small Vessel Base and Joint

Material Quality

Sony Anggara

, Topan Firmandha

, Rizqi Fitra H.

and Akbar Rakanda

Division of Research and Development, PT. Biro Klasifikasi Indonesia, Yos Sudarso, Jakarta, Indonesia

Tanjung Priok Branch, PT. Biro Klasifikasi Indonesia, Yos Sudarso, Jakarta, Indonesia

Keywords: HDPE, Destructive Test, Non Destructive Test, Ship, Weld Quality.

Abstract: The use of HDPE as an industrial material has been widely used and often encountered daily, ranging from

plastic bags, bottles, to clean water pipes. However for industries with larger objects (small ship industry)

HDPE has not been widely worked on. For national shipping industry, HDPE boat have not developed much,

because most of the raw materials for HDPE sheets are still imported, making HDPE boat more expensive

than FRP boat (even though the building of FRP ships is prohibited due to the issue of environmentally

damage). HDPE as a new/alternative material for boat must meet shipbuilding standards regulated in the

Classification rules, including the quality of base and welding joint of HDPE. The experiment was carried out

by testing HDPE joints with an extrusion type welding with 15mm thickness by bending and tensile tests,

using acceptance criteria on DVS 2203-5 and TL/IRS Rules, the results showed that in general the DT method

on HDPE welded joints failed due to less of joint and full penetration of the bevel. Meanwhile, to find out

defects in welds using the NDT method, a reference study was carried out which refers to the ASTM

E3044:2016 standard for UT testing of polyethylene butt fusion joints.

1 INTRODUCTION

Ship class approval generally consists of design

verification and supervision of the ship construction

at fabricator. Design assessment can be done clearly

by checking the scantling according to class rules

requirement or existing standards such as (ISO-

12215, 2020). Meanwhile, Challenges actually arise

in the shipbuilding process. Supervision must be

carried out intensively to ensure the strength of the

ship. One of the most importance step is including the

welding quality. Unfortunately, based on

observations in the field, most HDPE welders work

only based on experience and a trial / error.

Moreover, condition is getting worse since there

are many HDPE raw materials on the market that are

not comply with the minimum standard properties.

This lead major affects to the global strength of the

ship. Although the proposed design already meets the

minimum standard, the risk of failure remains if the

quality of the manufacturer is not guaranteed

This fact becomes an exclusive challenge for BKI

considering that there is no specific guideline yet of

BKI to ensure the fabrication quality of HDPE ship.

For this reason, comprehensive studies are needed

including welding standards and testing through the

DT (Destructive Test) and NDT (Non-Destructive

test) methods.

2 METHODOLOGY

This study was initiated with literature reviews and

discussions with several experts so that related

references regarding welding preparation and process

standards, welding defect criteria, and welding

quality testing have been obtained. This information

can be used as a basis for establishment of welding

procedures in fabrication.

2.1 Weld Joint Standard

Weld Joint for HDPE material need special treatment

since it differs to metal. The specific reference below

can be used as the basis of HDPE welding standard

for the ship.

2.1.1 Simona Welding

Welding standards in accordance with (Simona,

478

Anggara, S., Firmandha, T., H., R. and Rakanda, A.

HDPE as a New Alternative Material for Small Vessel Base and Joint Material Quality.

DOI: 10.5220/0011815200003575

In Proceedings of the 5th International Conference on Applied Science and Technology on Engineering Science (iCAST-ES 2022), pages 478-482

ISBN: 978-989-758-619-4; ISSN: 2975-8246

20011) contain brief guidelines regarding welding

methods of thermoplastic materials, weld defects, and

other substantial aspect for HDPE welding. For

extrusion welding method which commonly used in

some fabricators, HDPE filler wire is heated. Several

aspects that need to be considered according to

reference (Simona, 20011) are as follows:

 Temperature range for welding HDPE (PE-

HD) is 250 - 300

 Filler wire material must be the same as the

base material

 Cleanliness of base materials

 welding rate

 welding pressure

2.1.2 American Welding Society

(AWS-B2.4, 2012) is used as a reference for the

preparation of WPS (Welding Procedure Standard).

The items in the WPS include:

 Thickness of the material

 Range qualification (Thickness test pieces, and

base material)

 Test preparation (Number of test pieces for

each test)

 Bevel type

 Weld test specimens

 Welding filler

 Temperature factor

 Pressure factor

 Gas welding

 Electrical (current and voltage)

 Welding speed

2.1.3 DVS (DVS 2207-1, DVS 2207-4)

DVS (Die Verbindungs Spezialisten) is an

international standard regarding welding procedure

which is mostly used by HDPE ship builders as a

reference for welding HDPE materials. The types of

welding used by the builder can be either fusion

welding (DVS 2207-1, 2007) for large panels (hull

and deck panels joints) or extrusion welding (DVS

2207-4, 2007) for smaller and more complicated parts

(e.g., stiffener and joint joints). floors)

2.2 Weld Defects

In this study, Imperfection in thermoplastic weld

joints can be assess by referring to (DVS 2202-1,

2008) for acceptance criteria

In general, provisions regarding Internal quality

control, for preparation before fabrication, need to be

carried out to avoid welding defects. The provisions

can refer to the (IRS, 2021) Guidance with several

consideration as follows:

 HDPE material must be an approved type, and

there is no material installed on the ship that

can affect other installed materials.

 The shipyard must keep verifiable records of

material certificates from supplier, and keep

samples of each deliverable materials.

Materials must be stored according to the

manufacturer's instructions.

 Manufacturing/shipyard must comply with

welding requirements in accordance with

international/class standards

 WPS and NDT can refer to international

standards (ISO, EN, PD CENT/TS), as well as

HDPE welders must be certified according to

recognize standards

2.3 Destructive Test

Destructive tests are carried out on HDPE parent base

material and its welding joints. Types of the tests

carried out in this study is covering bending and

tensile test (i.e., base material, weld joint material to

longitudinal and transversal direction). There are 6

specimens for bending test. 2 specimens for tensile

base material, 5 specimens for tensile with transverse

weld joint and 1 specimen for tensile with

longitudinal weld joint. The dimension and shaped of

the specimens are determined in accordance with

(DVS 2203-5, 1999) for bending test and (ASTM

D638, 2014) for tensile test. Meanwhile, the

circumstance condition as per Table 1 has been set in

laboratory.

Table 1: Condition of testing.

Paramete

Value

Humidit

60% RH

Temperature 26.5

Pre

aration

(

Bendin

Test

)

DVS 2203-5: 1999

Pre

aration

(

Tensile Test

)

DVS 2203-2: 2010

2.4 Non-Destructive Test

Referring to the (ASTM E3044, 2016) standard for

UT of polyethylene butt fusion joints, it is explained

that ultrasonic testing for thermoplastic materials in

general can be done by 2 methods, namely PAUT

(Phased Array Ultrasonic Testing) and TOFD (Time

of Flight Diffraction). The two methods are illustrated

in Figure 1 and 2 below.

HDPE as a New Alternative Material for Small Vessel Base and Joint Material Quality

479

Figure 1: TOFD Examination.

Figure 2: PAUT Examination.

2.5 Material Sampling

Based on the manufacturing certificate, material

samples are produced in 1 batch (20 sheets) with the

following properties:

Table 2: Material Properties Material HDPE.

Test Value Unit

Specific gravit

0.955 g/cm3

Tensile Stren

th 25.84 N/mm2

Elon

ation at

iel

9.7 %

Modulus of Elasticit

1160 N/mm2

Elongation at brea

>300 %

Notched impact strength 10.39 mJ/mm2

3 RESULT AND DISCUSSION

3.1 Bending Test (Transverse Joint)

According to the test standards on (DVS 2203-5,

1999), the weld joint will be approved if comply with

acceptance criteria which there is no crack in the

material that has been subjected to a bending test at

160

angle.

The test was carried out on 6 specimens with the

result that all specimens cracked at a bend angle of

160

. This means that the specimen being tested does

not meet the minimum requirements of (DVS 2203-5,

1999) or fails. The initial hypothesis is that the quality

of the weld on HDPE material does not meet the

requirements of the weld strength, the welding

process does not fully penetrate into entire bevel so

that there is a bevel that is not filled by the filler

material. Thus, it will lead an impact on the strength

of the weld itself. There result of bending test can be

seen in Table 3.

Table 3: Bending test result.

ID Width

[mm]

Height

[mm]

Area

[mm]

Max

Load

[N]

Bending

Stress

[MPa]

1 20.97 15.32 321.26 1468.8 44.765

2 20.77 15.35 318.82 1561.3 47.854

3 20.95 15.44 323.47 1568.2 47.098

4 20.31 15.36 311.96 1328.3 41.581

5 20.79 15.28 317.67 1370.0 42.336

6 20.94 15.43 323.10 1231.6 37.057

Visualization of bending test result in Figure 3

show that 6 samples experienced cracks in the weld

area. This indicates that the weld area is the weakest

point of the specimen.

Figure 3: Bending test in Laboratory.

3.2 Tensile Test (Base Material)

The results of tensile test (base material) aim to see

whether the raw material used meets the requirements

standard of HDPE material or not. Since there are fact

that counterfeit material exist on market. The

acceptance criteria used are the standards from (Turk

Lloyd Class, 2014) and (IRS, 2021) where the

minimum ultimate tensile stress requirement is 24

MPa. The results of the 2 specimens tested were 24.07

MPa and 24.78 MPa, which means that the raw

material used meet with the standard. See Table 4 for

ultimate stress result and Figure 4. For elongation-

load behavior

iCAST-ES 2022 - International Conference on Applied Science and Technology on Engineering Science

480

Table 4: Tensile test result for base material.

ID Width

[mm]

Thickness

[mm]

Max

Load

[N]

Max.

Stress

[MPa]

1 30.19 15.35 11154 24.07

2 30.16 15.43 11532 24.78

Figure 4: Elongation base metal of Tensile test.

This has been also confirmed by similar tests

performed in (Jamal and Aryawan, 2015) which

obtained a determination that the magnitude of the

yield strength of HDPE plastic is at 17.12 MPa and

Tensile strength is at 24.82 MPa. Those known as

standard properties of HDPE.

3.3 Tensile Test (Transverse Joint)

The results of the tensile test (Transversal) aim to see

the strength of the weld joint compared to base

material. From 5 tested specimens, all failed/broken

at the welded area with tensile strength of around 19-

22 MPa. This means that the strength of weld joint is

lower than minimum tensile strength of raw material

(24 MPa). This indicates that the welding process

carried out was poor so that the bevel is not

completely filled (see Figure 5), which affects the

strength of the weld itself.

Table 5: Tensile test result for transverse weld joint.

Width

[mm]

Thickness

[mm]

Max

Load

[N]

Max.

Stress

[MPa]

Elong

ation

[%]

1 30.03 15.34 9054 19.65 3.48

2 30.15 15.44 8315 17.86 3.47

3 30.26 15.31 10411 22.47 2.53

4 30.31 15.30 9815 21.16 2.13

5 30.26 15.34 9655 20.80 2.62

From a technical point of view, fracture in the

weld area is allowed if the tensile strength of the weld

exceeds the value of the tensile strength of the raw

material, so it can be concluded that the welding

process carried out does not meet the (Turk Lloyd

Class, 2014) and (IRS, 2021).

Figure 5: Tensile test result (transverse weld joint).

3.4 Tensile Test (Longitudinal Joint)

Longitudinal tensile test aims to see the strength at

weld area. However, in this case, the cut specimen

leaves raw material beside the weld area. When

compared with other mode of tensile test, this

longitudinal tensile test is less able to conclude the

actual results because the tensile specimen is not pure

from the weld area.

Table 6: Tensile test result for longitudinal weld joint.

ID Width

[mm]

Thickness

[mm]

Max

Load

[N]

Bending

Stress

[MPa]

1 25.28 15.52 10798 27.522

4 CONCLUSIONS

In testing materials and HDPE weld joints, the

standards commonly used by domestic builders are

(DVS 2202-1, 2008) for imperfection criteria of

welded joints and (DVS 2203-5, 1999) for bending

test criteria. While the tensile test can refer to (ASTM

D638-14, 2014) and (ISO-527, 2019).

By referring to the standard above, it can be

concluded that HDPE welded joints failed to DT test,

due to weld imperfection and not full penetration of

the bevel. Poor welding quality can be caused by

inappropriate travel speed. Travel speed that is too

fast causes the filler to not penetrate completely,

allowing the formation of cavities inside the joint. On

the other hand, a travel speed that is too slow will

cause large area of base material that affected by heat

(Maki, 2015). It is clear that the quality of the weld is

importance and a bad weld can be catastrophic for the

structure.

To avoid such welding defects, things that must be

considered regarding the welding process are as

follows:

 Regarding specimen preparation, it must be

ensured that the weld material fully penetrates

so that it fills the bevel completely and

HDPE as a New Alternative Material for Small Vessel Base and Joint Material Quality

481

thoroughly. This can be evaluated at the time of

making pre-WPS, if the welding test results do

not meet the requirements, the WPS will be

returned and to be revised with new welding

parameters.

 References related to thermoplastic

joints/welding can follows the international

standards mentioned in Table 4.3.3 of the (IRS,

2021) Guidelines (EN, ISO, PD CEN/TS)

Lastly, Due to the different nature from steel, NDT

testing of steel cannot be applied to HDPE. According

to the (ASTM E3044, 2016) standard, the UT test for

polyethylene butt fusion joints can be carried out

using the PAUT and TFOD methods. However, so far

there has not been found a laboratory that capable of

conducting NDT tests for HDPE materials using the

PAUT and TFOD methods in Indonesia. Commonly,

PAUT is used for pipe NDT test. However, in practice

PAUT can be done through conventional UT by

modifying the prob.

ACKNOWLEDGEMENTS

Our sincere gratitude and appreciation to Iqra Visindo

Shipyard who support in providing material and

specimen as well as share their knowledge and

experience of building boat HDPE based material.

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Properties of Plastics. United States

ASTM E3044-16 (2016). Standard Practice for Ultrasonic

Testing of Polyethylene Butt Fusion Joints. United

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AWS B2.4 (2012). Specification for Welding Procedure

and Performance Qualification for Thermoplastics.

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