Presentation

HDPE Liners(High Density Polyethylene)

and Tank Bottom Preparation

Prepared by: John Saji, Senior Project Inspector (Civil)

Wasea Bulkplant ProjectC

RRAPIU

Table of Contents

Introduction & Purpose

References

HDPE Raw Materials

Inspection Prior to installation

Installation

Testing and Inspection

Final Inspection

Lesson Learned

Conclusion

The HDPE (High Density Polyethylene) geomembrane is a

material which is widely used for the tank foundations. This

product is a high quality geomembrane to meet the

requirements of lining application and to protect the

environment from chemical contaminations.

It is an impervious vapor barrier which can be used as water proofing membrane for oil tank foundations to prevent the intrusion of oil contamination to the soil.

Introduction

Purpose

SAUDI ARAMCO STANDARDS SAES-A-114 – Excavation and Backfilling SAES-Q-001 – Criteria for Design and Const. of Concrete

Structures 32-SAMSS-005 - Manufacture of Atmospheric Tanks

INT’L STANDARDS API-650 – Welded Steel Tank for Oil Storage

SATIPs (SAUDI ARAMCO Typical Inspection Plan) SATIP-A-114-001 SATIP-Q-001-02 SATIP-HDPE-001- Installation of HDPE Liners

LESSON LEARNED

1. CRWR-088 – Tips on HDPE Installation

References

Two types of raw materials, natural resin and masterbatch of the concentrated carbon black along with the other additives, are used for the manufacturing of Geomembrane.

Natural resin is the main material of the product.

Masterbatch contains carbon black, stabilizer, anti-oxidant and UV absorber. These raw materials are mixed with the natural resin at an appropriate portion during the manufacturing.

HDPE Raw Materials

Visual inspection of goods at Store Yard: All materials reached at site yard, shall be inspected and

checked with the roll numbers, batch number and manufacturing time and date, together with the QA/QC certificate. Material handling and preservation to be controlled during storage.

Visual Inspection at Job Site: The HDPE membrane shall be checked against the mechanical

damages such as puncture, cuts, severe scratches etc., occurred in handling the materials.

Sub grade Visual Inspection: Before starting the installation of the membrane, the sub

grade must be thoroughly checked. Surface to be lined shall be smooth and free of all rocks,

stones, sticks, roots, sharp objects or debris of any kind. Surface to be lined should provide a firm, unyielding

foundation for the membrane with no sudden, sharp or abrupt change or break in grade.

Inspection Prior to Installation

The surface over which the liner is installed shall be free

from all debris, vegetation and sharp projections.

The surface shall be prepared and compacted with a

minimum of 98 % compaction.

The field density test, lines and levels are inspected.

Installation

The sump is made according to the drawing. The size , shape and slopes are to be checked. The position and slope of leak detection pipes are to be verified.

Leak Detection SumpRef. Drg. VA-384064 rev 001

The sump is filled by stone pebbles and the leak detection pipe mouth is covered by geotextile to prevent the sand in to pipe.

The liner should be cleaned, the over lap of each piece is in between 100 and 150 mm ,the number of joints shall be minimized.

Double wedge welding machine is a plastic welding machine. This should be calibrated, the welder shall be qualified. The machine shall be verified whether it is working or not on daily basis by sample welding. Before making field joints, all wrinkles shall be removed .Joining of surfaces shall use a hot double fusion welding and remaining by extrusion weld.

Used to repair large holes, tears and destructive locations All patches shall extend at least three inches beyond the edges of the defect and all corners of patches shall be rounded.Grinding and welding is used to repair section of extruded fillet seams.Spot welding or seaming is used to repair small tears, pinholes or other minor localized flaws.

Extrusion welding

Visual Inspection

Vacuum Testing

Spark Test

As welded seams are visible on the surface any suspected areas may easily be noted. Such areas, breaks or holes should be marked and repaired.

All field seams over their full length will be tested by

using

vacuum test unit or spark tester, where applicable. The

purpose of testing is to check the seams for leaks and to

ensure leak proof water tight containment sealing system.

In case of test failure, the failed portion of the seam shall

be

identified and marked for repairs. After repairing it is re-

tested until a passing result is obtained.

Testing and Inspection

Vacuum testing machine shall be calibrated. The technician should be familiar with it. If any damage or leak can be marked and rectified .

Prior to covering the membrane with sand, the membrane installed shall be checked thoroughly to be backfilled that day. This is the final inspection for the installation of the lining system. This final inspection is made to make sure there exists no damage or leak that was found, or caused after the previous repair is left un- repaired.

Final Inspection

Clean sweet sand of same grade for concreting with a compact fill of 150mm thick layers shall achieve dry density required by project specifications.

16

Top layer of sand-cement of 100 to 150 mm thick in which 3% of cement in terms of weight shall be compacted according to 32-SAMSS-005 Appx B.2.6- 1,2,3

Lesson Learned

Leak-Barrier Burned During Welding of Tank BottomFlexible membrane (High Density Poly Ethylene liner) was installed

as a leak-barrier to above-ground API 650 storage tank bottom.  HDPE lining was extended onto upper horizontal surface of foundation with asphalt impregnated fiber board on top. During welding of tank bottom plate, there was heat transfer that led to burning of HDPE lining, in spite of a Bitumen impregnated board placed between lining and bottom plate.

CRWR-088 – Tips on HDPE Installation

Lesson Learned (cont’d)

Previous Design (Sect ion)

TANK BOTTOM PLATE

BITUMEN IMPREGNATED FIBER BOARD (12 mm)

CURRENT HDPE LINER EXTENDED ON UPPER SURFACE OF FDN

TANK RC FDN

Lesson Learned (cont’d)

Revised Design (Sect ion)

TANK BOTTOM PLATE

BITUMEN IMPREGNATED FIBER BOARD (12 mm)

HDPE LINER SHALL BE EXTENDING TO THE INTERNAL TOP EDGE OF THE RING FOUNDATION

TANK RC FDN

CONCLUSION

THANK YOU