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OISD-STANDARD-160 First Edition August, 1993. FOR RESTRICTED CIRCULATION

PROTECTION TO FITTINGS MOUNTED ON

EXISTING LPG TANK TRUCKS

Prepared by: COMMITTEE ON LPG TANK TRUCK MODIFICATIONS, DESIGN & OPERATION

OIL INDUSTRY SAFETY DIRECTORATE 7TH FLOOR, NEW DELHI HOUSE

27, BARAKHAMBA ROAD NEW DELHI - 110 001.

NOTE OIL INDUSTRY SAFETY DIRECTORATE (OISD)

publications are prepared for use in the oil and gas industry under the Ministry of Petroleum and Natural Gas. These are the property of Ministry of Petroleum and Natural Gas and shall not be reproduced or copied and loaned or exhibited to others without written consent from OISD.

Though every effort has been made to assure the

accuracy and reliability of data contained in these documents, OISD hereby expressly disclaims any liability or responsibility for loss or damage resulting from their use.

These documents are intended only to supplement and

not replace the prevailing statutory requirements.

FOREWORD The Oil Industry in India is 100 years old. Because of various

collaboration agreements, a variety of international codes, standards and practices have been in vogue. Standardisation in design philosophies and operating and maintenance practices at a national level was hardly in existence. This, coupled with feed back from some serious accidents that occured in the recent past in India and abroad, emphasised the need for the industry to review the existing state of art in designing, operating and maintaining oil and gas installations.

With this in view, the Ministry of Petroleum and Natural Gas in 1986

constituted a Safety Council assisted by the Oil Industry Safety Directorate (OISD) staffed from within the industry in formulating and implementing a series of self regulatory measures aimed at removing obsolescence,standardising and upgrading the existing standards to ensure safe operations. Accordingly, OISD constituted a number of functional committees of experts nominated from the industry to draw up standards and guidelines on various subjects.

The present document on “Protection to Fittings Mounted on Existing

LPG Tank Trucks’ has been prepared by the Committee on “LPG Tank Truck Modifications, Design and Operation’. This document was prepared based on the accumulated knowledge and experience of industry members and the various national and international codes and practices.

Correspondence from industry members may be addressed to:

The Co-ordinator

Committee on LPG Tank Truck Modifications, Design and Operation

OIL INDUSTRY SAFETY DIRECTORATE 7TH FLOOR, NEW DELHI HOUSE

27, BARAKHAMBA ROAD NEW DELHI - 110 001..

COMMITTEE

ON

LPG TANK TRUCK MODIFICATIONS, DESIGN AND OPERATION

LIST OF MEMBERS -------------------------------------------------------------------------------------------------------------------------------- NAME DESIGNATION/ORGANISATION STATUS -------------------------------------------------------------------------------------------------------------------------------- S/Shri R.K. Singh DGM (Distribution), BPCL Leader V.K. Allawadi Chief LPG Mgr.(OPS), IOCL Member

S.V. Sahni Chief OPS, Mgr., HPCL Member S.C. Gupta Joint Director (OISD) Member-Co-ordinator -------------------------------------------------------------------------------------------------------------------------------- In addition to the above several other experts from industry contributed in the preparation, review and finalisation of this document.

PROTECTION TO FITTINGS MOUNTED ON EXISTING LPG TANK TRUCKS

CONTENTS

------------------------------------------------------------------------------------------------------------------------ SECTION DESCRIPTION ------------------------------------------------------------------------------------------------------------------------ 1.0 INTRODUCTION 2.0 SCOPE 3.0 LPG TANK TRUCK FITTINGS 3.1 OPENINGS/NOZZLES 3.2 SAFETY RELIEF VALVE (SRV) 3.3 EXCESS FLOW CHECK VALVE (EFCV) 3.4 PRESSURE GAUGE 3.5 FIXED LEVEL GAUGE/DRAIN NOZZLES 3.6 ROTO GAUGE 3.7 LIQUID/VAPOUR PIPING 3.8 HEIGHT BARRIER 3.9 MOUNTING GLOSSARY ANNEXURES --------------------------------------------------------------------------------------------------------------------------------

PROTECTION TO FITTINGS MOUNTED ON EXISTING LPG TANK TRUCKS

1.0 INTRODUCTION A large number of road fed bottling plants have been put up by the Oil Industry during the last five years. The industry fleet of tank trucks has also increased considerably during the last decade. Prior to 1981, there were no separate statutory regulations governing design, fabrication, operation and licensing of LPG tank trucks. After introduction of SMPV Rules - 1981, old tank trucks which were conforming to different codes and standards have been modified to the extent possible and new tank trucks have been fabricated and licensed in line with the SMPV Rules, 1981 and Petroleum Industry Standards. Industry, CCEE and OISD have been analysing LPG tank truck accidents from time to time. Based on the experience gained some modifications have already been introduced on piece meal basis by the Industry members individually. Various road accidents involving LPG tank trucks have established that their fittings get damaged due to heavy impact in the event of an accident resulting in leakage of LPG which, in turn, poses serious threat to public life and property. There has hardly been any damage to the bullets and it is the fittings which mostly give way. An OISD committee consisting of members drawn from Oil Industry therefore discussed this subject in detail and after deliberations has identified the problems and prepared these recommendations for improvements of the existing LPG tank truck fleet to prevent leakage of LPG in the event of LPG tank trucks overturning on the road. 2.0 SCOPE SMPV Rules - 1981 lay down design, fabrication, operating procedure for carrying compressed gases.

This standard stipulates actions required for improving some of the provisions of these rules like fittings, pressure relief, emergency shut off valves, liquid level gauging device and pressure gauge so as to reduce chances of accidental damage to various fittings mounted on LPG tank truck. Some of the recommendations envisage updating existing Standards and would require amendment of the exiting Statutory Rules Viz. Static and Mobile Pressure Vessels (unfired) Rules 1981. The provisions which are not in conformity with SMPV Rules- 1981, therefore will be made applicable after the Rules are formally amended. The standard excludes new tank trucks which will be fabricated in coming years as they will be conforming to more stringent standard which is currently under development. 3.0 LPG TANK TRUCK FITTINGS 3.1 OPENINGS/NOZZLES LPG tank truck is provided with the following openings/nozzles: I) Safety Relief valves ii) Excess flow check valves in

the liquid and vapour lines and pressure gauge nozzle.

iii) Pressure gauge (Provided in

the vapour space of the vessel)

iv) Temperature gauge

(Provided in the liquid space)

v) Rotogauge (to measure the

percentage of liquid in the vessel.

vi) Manhole with cover. vii) Fixed level gauge viii) Drain point at the bottom. ix) Liquid/Vapour manifold. 3.2 SAFETY RELIEF VALVE (SRV) Each tank truck is provided with two or more SRVs for providing the relieving capacity under excess pressure. The SRVs are mounted on the top surface of the vessel either in the recessed fittings or at the shell level with head projecting out. In the event of an accident causing the tank truck to fall off the road and topple, there is a possibility that Safety Relief Valves which projects out can hit against a hard surface and get damaged or even come out of the nozzles as adequate protection as envisaged in the rules has not been provided. To prevent this from happening, the following measures shall be adopted:

I) The SRV of an LPG tank truck shall be provided in a recessed cup formation. Alternatively, it may be adequately protected by providing a guard allround as per the CCE approved procedure for modification (Ref.Annexures I and II) and design given in Fig.No.1. Suitable rain caps shall also be provided in case of recessed cup.

ii) SRV shall be replaced by a new

SRV every ten years. If found defective during any of the earlier yearly inspections, it shall be replaced earlier.

iii) Unstamped (Uncertified) SRVs

shall not be used. iv) At the time of yearly

inspection/each opening, the threads of the valve and coupling shall be checked by an Inspection Agency/Competent Person using “Go/No Go”

gauges. SRV shall be tightened to the required torque specified for its size so as to obtain minimum engagement of 5-6 threads by hand tightening and another 1-2 threads by spanner tightening.

LPG tank trucks shall carry SRV certificates issued by Inspection Agency/Competent Persons which apart from test date and set pressures, shall also include the following information: a) The number of threads

engaged in its coupling. b) The number of threads outside

its coupling. c) Torque applied for tightening. d) Identification mark of SRVs. 3.3 EXCESS FLOW CHECK VALVES (EFCVs.) Each liquid/vapour pipeline and pressure gauge nozzle shall be provided for excess flow check valve. Excess flow check valve shall be of hinge unit type or internal flow type. EFCVs before fitment, shall be checked using “Go/No Go”, gauges and shall be tightened to the required torque specified for the size to obtain minimum engagement of 5-6 threads through hand tightening and another 1-2 threads by spanner tightening. In addition to operation checks on EFCV at loading/unloading basis, EFCV shall also be examined for its proper operation alongwith SRV, once a year by competent person. Each EFCV shall be replaced by a new EFCV every ten years. If found defective during operation or any of the earlier inspection, it shall be replaced at that time itself i.e., earlier than ten years. 3.4 PRESSURE GAUGE The functional parts of EFCV of pressure gauge shall remain within its coupling. In addition, the pressure gauge if not provided in recessed cup shall be adequately protected with a shroud.

3.5 FIXED LEVEL GAUGE/DRAIN NOZZLES With experience these fittings have been found to be redundant. Therefore, to minimise the openings in the tanker, these fittings shall be plugged (After necessary amendment to the SMPV Rules, 1981). Plugging shall be approved by Competent Persons/Inspection Agency. 3.6 ROTO GAUGE These fittings shall be housed in a recessed cup formation, when fitted on longitudinal sides of vessel to avoid any accidental damage to bleed valve or seal. The rotogauge shall also be protected with a provision of hinged cover of 5 mm thick plate. 3.7 LIQUID/VAPOUR PIPING The pipes shall conform to the ASTM A-106B, schedule 80 standards. Liquid/Vapour piping shall be single piece and the end flanges shall be of ASA-300 rating. Metal jacketted gasket shall be used for the piping system. In addition, sturdy guard shall be provided between the propeller shaft and the elbow of the piping. Adequately strong arrangement shall be provided to fix the piping rigidly to the bullet/chassis to minimise the effect of vibrations. 3.8 HEIGHT BARRIER Whenever cabin height is less than the height of the vessel and fittings on top of it, a height barrier shall be provided all along the width of the cabin in the form of a cage either 50mm diameter pipe or 50 X 50 X 3 MM angle frame on the top of vessel and

within the height regulation of Road Transport Authority. 3.9 MOUNTING U-Bolts used for mounting of the mounting of the pressure vessel on the chassis shall conform to ASTM 193 B7 and the nuts to A194 Gr.2H. The number and size of bolts should be as per the design requirements for the particular chassis and load thereon. GLOSSARY 1. The term “LPG” i.e., Liquefied

Petroleum Gas as referred in this standard refers to a mixture of gaseous hydrocarbon fractions which get into liquid phase under pressure at ambient temperature with a maximum RVPof 120 psig at100Deg. F(8.45 Kg/CM2g at 37.8 Deg.C) conforming to IS-4576.

2. The term “Bullet” refers to

horizontal cylindrical pressure vessels with dished ends on LPG service.

3. “Inspection Agency/Competent

Person” means the Agency or Person recognised by the Statutory Authority for the purpose of inspecting the vessel and its fittings in accordance with the approved Design, Specifications or Code and mandatory requirements.

4. “Statutory Authority” in this

case is normally Chief Controller of Explosives (CCE) and/or his representatives only.

ANNEXURE - I

PROCEDURE * FOR MODIFICATION TO

EXISTING LPG ROAD TANKERS

I) Degas the storage vessel (Bullet ) taking standard safety precautions. ii) Remove the fittings. iii) Fabricate the pad plates/protection shroud plates/gussets plates as shown in draining B-

1382 (Rev-A). All gas out edges to be ground smoothly. Check for laminations, if any in the plates.

iv) Weld the pad plates over the Bullet and then the shroud plates/gussets to the pad plate

strictly as shown in drg.: B-1382 (Rev-A) using low hydrogen 7018 Electrodes. Check for thickness of weld with standard welding gauge.

v) Locally stress relieve the area around the safety fittings. vi) Carry out pneumatic test of the bullet at 6 Kg/Cm2 after fixing all the fittings. vii) Test all fillet welds with magnetic particle test. viii) Hydrotest the Bullet up to test pressure. ix) The entire work to be supervised and certified by CCOE approved third party Inspection

Agency. * (Approved by CCE)

ANNEUXRE -II

CALCULATIONS FOR SUITABILITY OF SHROUD AROUND SAFETY VALVES

REF. DRAWING OF SHROUD ARRANGEMENT (B 1382 REV. - 0)

DESIGN DATA : MAX.SIZE & DIA. ROAD TANKER AT 40 KMPH TOPPLING OVER ASSUME MAX. LOADING DUE TO MOTION=3G TANK : 2350 mm I/D X 9254 mm Overall Length, mounted on Double Axle Trailor : Total Payload = 18000 Kgs (39672 lbs) : Permissible GLW. = 35000 Kgs (77140 lbs) EFFECTIVE WEIGHT : GLW-(Wt.of Cabin + Prime Mover + Vth Wheel) = 35000 Kgs. (-) 6000 Kgs. = 29000 Kgs. = (63916) lbs) SHROUD - MOC : CS A 515 Gr.70, Shear Stress 1/3 of UTS : i.e, 1/3 of 70,000 psi : Stress Value “S” : Length “L” 1000mm = 40” : Width ‘B’ 600 mm = 24” :’E’ = Joint efficiency for butt weld (CI UW - 12) = 0.6 : R = Height of shroud above C.G. of Tank = 50” THICKNESS ‘’t’’ UNDER : 3 X W t = ------------------------ (3G effect) 2(L + B) X S X E

: = 3 X 63916 ----------------------------------- = 0.107”=2.7mm.....(1) 2(40+20) X 23333 X 0.6 ‘‘t” DUE TO THE BENDING MOMENT : W x R 63916 x 50 -------------------- = --------------------------- (L x B)XSXE 960 X 23333 X 0.6 = 2237 = 6.04 mm ......(2) TOTAL THICKNESS REQUIRED =2.7+6.04 = 8.74mm Provided 10mm (Safe)

CALCULATIONS FOR SUITABILITY OF SHROUD AROUND SAFETY VALVES

DATE: 21-3-92 A-1504

REV

0

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