Workshop fabricated steel tanks - Part 2: Horizontal cylindrical single skin and double skin tanks for the aboveground storage of flammable and non-flammable water polluting liquids

This document specifies the requirements for metallic shop fabricated cylindrical, horizontal steel tanks, single and double skin for the aboveground storage of water polluting liquids (both flammable and non-flammable) within the following limits:
-   from 800 mm up to 3 000 mm nominal diameter and,
-   up to a maximum overall length of 6 times the nominal diameter and,
-   for liquids with a maximum density of up to 1,9 kg/l and,
-   with an operating pressure (Po) of maximum 1,5 bar (abs.) and,
-   where double skin tanks with a vacuum leak detection system are used the cinematic viscosity of the stored media shall not exceed 5 ´ 10-3 m2/s.
This document is applicable for normal ambient temperature conditions (- 20 °C to + 50 °C). Where temperatures are outside this range, additional requirements need to be taken into account.
This document is not applicable for the storage of liquids having dangerous good classes listed in Table 1 because of the special dangers involved.
Table 1 - List of dangerous goods the storage of which are not covered by this document
UN-classification   Storage media
Class 1                     Explosives
Class 4.2                  Substances liable to spontaneous combustion
Class 4.3                  Substances which in contact with water emit flammable gases
Class 5.2                  Organic peroxides
Class 6.2                  Infectious substances
Class 7                   Radioactive material, hydrocyanic or hydrocyanic solvent liquids, metalcarbonyls, hydrofluoracid, bromide liquids
NOTE   The classifications referred to are those adopted by the United Nations Committee of Experts on the Transport of Dangerous Goods (not to be interpreted as tank classes described in 3.1.4).
This document does not cover the installation of tanks which might be subject to local regulations involving pollution control.

Werksgefertigte Tanks aus Stahl - Teil 2: Liegende zylindrische ein- und doppelwandige Tanks zur oberirdischen Lagerung von brennbaren und nichtbrennbaren wassergefährdenden Flüssigkeiten

Dieses Dokument enthält Anforderungen an werksgefertigte zylindrische, liegende, ein- und doppelwandige Stahltanks zur oberirdischen Lagerung von (brennbaren und nichtbrennbaren) wassergefährdenden Flüssigkeiten mit folgenden Anwendungsgrenzen:
-   Nenndurchmesser von 800 mm bis 3 000 mm und
-   maximale Gesamtlänge bis zum 6fachen des Nenndurchmessers und
-   für Flüssigkeiten mit einer maximalen Dichte von 1,9 kg/l und
-   mit einem Betriebsdruck (Po) von maximal 1,5 bar (abs.) und
-   bei Verwendung von doppelwandigen Tanks mit einem Vakuum-Leckanzeigesystem darf die kinematische Viskosität des Lagermediums 5 ´ 10-3 m2/s nicht übersteigen.
Dieses Dokument gilt bei üblichen Ungebungstemperaturen (-20 °C bis +50 °C). Für Temperaturen außerhalb dieses Bereichs müssen zusätzliche Anforderungen berücksichtigt werden.
Dieses Dokument gilt nicht für die Lagerung von Flüssigkeiten der in Tabelle 1 aufgeführten Gefahrgutklassen wegen der von ihnen ausgehenden besonderen Gefahr.

Réservoirs en aciers fabriqués en atelier - Partie 2: Réservoirs horizontaux a simple et double paroi pour le stockage aérien des liquides inflammables et non inflammables polluant l'eau

Le présent document spécifie les exigences applicables aux réservoirs en aciers, cylindriques, horizontaux,
fabriqués en atelier, a simple et double paroi, pour le stockage aérien de liquides polluant l'eau (inflammables et
non inflammables), et compris dans les limites suivantes :
.diametre nominal compris entre 800 mm et 3 000 mm ;
.longueur maximale d'encombrement égale a 6 fois le diametre nominal ;
.pour les liquides présentant une masse volumique maximale égale a 1,9 kg/l ;
.avec une pression de service (p o ) maximale de 1,5 bar (absolue) ; et
.lorsque des réservoirs a double paroi, munis d'un systeme de détection de fuites du vide, sont utilisés, la
viscosité des liquides stockés ne doit pas etre supérieure a 5 × 10 -3 m 2 /s.
Le présent document s'applique dans des conditions normales de température ambiante (-20 °C a + 50 °C).
Lorsque des températures sont en dehors de cette plage, il convient que des exigences complémentaires soient
considérées.
Ce document ne s'applique pas au stockage de liquides appartenant aux classes de matieres dangereuses
énumérées au Tableau 1, en raison des dangers spécifiques engendrés.

Jekleni rezervoarji, izdelani v delavnici – 2. del: Vodoravni valjasti enoplaščni in dvoplaščni rezervoarji nadzemne izvedbe za gorljive in negorljive tekočine, ki onesnažujejo vodo

General Information

Status
Published
Publication Date
30-Apr-2005
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-May-2005
Due Date
01-May-2005
Completion Date
01-May-2005

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Workshop fabricated steel tanks - Part 2: Horizontal cylindrical single skin and double skin tanks for the aboveground storage of flammable and non-flammable water polluting liquidsRéservoirs en aciers fabriqués en atelier - Partie 2: Réservoirs horizontaux a simple et double paroi pour le stockage aérien des liquides inflammables et non inflammables polluant l'eauWerksgefertigte Tanks aus Stahl - Teil 2: Liegende zylindrische ein- und doppelwandige Tanks zur oberirdischen Lagerung von brennbaren und nichtbrennbaren wassergefährdenden Flüssigkeiten23.020.10UH]HUYRDUMLStationary containers and tanks13.300Varstvo pred nevarnimi izdelkiProtection against dangerous goodsICS:SIST EN 12285-2:2005enTa slovenski standard je istoveten z:EN 12285-2:200501-maj-2005SIST EN 12285-2:2005SLOVENSKI

STANDARD

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 12285-2February 2005ICS 23.020.10English versionWorkshop fabricated steel tanks - Part 2: Horizontal cylindricalsingle skin and double skin tanks for the aboveground storage offlammable and non-flammable water polluting liquidsRéservoirs en aciers fabriqués en atelier - Partie 2:Réservoirs horizontaux à simple et double paroi pour lestockage aérien des liquides inflammables et noninflammables polluant l'eauWerksgefertigte Tanks aus Stahl - Teil 2: Liegendezylindrische ein- und doppelwandige Tanks zuroberirdischen Lagerung von brennbaren undnichtbrennbaren wassergefährdenden FlüssigkeitenThis European Standard was approved by CEN on 17 December 2004.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36

B-1050 Brussels© 2005 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 12285-2:2005: E

EN 12285-2:2005 (E) 2 Contents Page Foreword......................................................................................................................................................................4 Introduction.................................................................................................................................................................5 1 Scope..............................................................................................................................................................6 2 Normative references....................................................................................................................................7 3 Terms, definitions, symbols and abbreviations.........................................................................................7 3.1 Terms and definitions...................................................................................................................................7 3.2 Symbols and abbreviations..........................................................................................................................9 4 Requirements...............................................................................................................................................11 4.1 Designation and purchaser's specification..............................................................................................11 4.2 Materials.......................................................................................................................................................11 4.3 Design...........................................................................................................................................................12 4.4 Tolerances....................................................................................................................................................14 4.5 Shell plate arrangement..............................................................................................................................14 4.6 Manholes and inspection covers...............................................................................................................14 4.7 Structural bolts............................................................................................................................................16 4.8 Tank fittings, pipes and nozzles.................................................................................................................16 4.9 Saddles, supports........................................................................................................................................16 4.10 Lifting lugs....................................................................................................................................................18 4.11 Fabrication....................................................................................................................................................18 4.12 Dangerous substances...............................................................................................................................21 4.13 Reaction to fire.............................................................................................................................................21 4.14 Durability......................................................................................................................................................21 5 Testing assessment and sampling methods............................................................................................21 6 Evaluation of conformity.............................................................................................................................21 6.1 General..........................................................................................................................................................21 6.2 Type testing..................................................................................................................................................22 6.3 Factory production control (FPC)..............................................................................................................23 7 Handling and installation............................................................................................................................24 7.1 Handling........................................................................................................................................................24 7.2 Installation....................................................................................................................................................24 8 Marking and labelling of the tank...............................................................................................................24 8.1 Marking of the tank......................................................................................................................................24 8.2 Tank certificate.............................................................................................................................................25 8.3 Documentation.............................................................................................................................................25 Annex ZA (informative)

Clauses of this European Standard addressing the provisions of the

EU Construction Products Directive................................................................................................................26 ZA.1 Scope and relevant characteristics...........................................................................................................26 ZA.2 Procedure(s) for the attestation of conformity of steel tanks.................................................................27 ZA.3 CE marking and labelling............................................................................................................................29 Bibliography..............................................................................................................................................................32

EN 12285-2:2005 (E) 3 Figures Figure 1 — Example of double skin aboveground tank, symbols.......................................................................10 Figure 2 — Shell plate arrangement for inner and outer skin..............................................................................14 Figure 3 — Examples for manholes........................................................................................................................15 Figure 4 — Example for a saddle support arrangement.......................................................................................16 Figure 5 — Example for marking............................................................................................................................24 Figure ZA.1 — Example CE marking information for a system 3 product..........................................................31

Tables Table 1 — List of dangerous goods the storage of which are not covered by this document..........................6 Table 2 — Tank classes.............................................................................................................................................8 Table 3 — Nominal wall thickness for inner and outer skin tanks, dished ends and compartment dished end....................................................................................................................................................13 Table 4 — Dimensions of manhole components...................................................................................................15 Table 5 — Dimensions of welded saddles.............................................................................................................17 Table 6 — Dimensions of saddle components......................................................................................................17 Table 7 — Loose saddles.........................................................................................................................................17 Table 8 — Types of welded joints...........................................................................................................................19 Table 9 — Test pressure Pt1 and Pt2........................................................................................................................21 Table 10 — Number of units and compliance criteria for initial and further testing.........................................22 Table 11 — Minimum frequency of testing for product testing and evaluation as part of FPC.......................23 Table ZA.1 — Relevant clauses...............................................................................................................................27 Table ZA.2 — Attestation of conformity systems..................................................................................................27 Table ZA.3a — Assignment of evaluation of conformity tasks (for system 3)...................................................28 Table ZA.3b — Assignment of evaluation of conformity tasks (for system 4)...................................................28

EN 12285-2:2005 (E) 4 Foreword This document (EN 12285-2:2005) has been prepared by Technical Committee CEN/TC 221 “Shop fabricated metallic tanks and equipment for storage tanks and for service stations”, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by August 2005, and conflicting national standards shall be withdrawn at the latest by November 2006. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association and supports essential requirements of Construction Products Directive (CPD)1). For the relationship with this Directive, see informative Annex ZA, which is an integral Part of this document. By application of this document presumption is given, that the Essential Safety Requirements of the CPD are met. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

1) Directive 89/106/EEC of the European Parliament and the Council of 21 December 1988 on the approximation of the laws of the Member States concerning Construction products (OJEC L 40).

EN 12285-2:2005 (E) 5 Introduction This document is part of a family of standards involving shop fabricated tanks and equipment for storage tanks and for service stations (compare listing below and bibliography). Normal ambient temperatures considered in this document are -20 °C to +50 °C. Where temperatures are outside this range it could become necessary to consider further requirements. These could include temperature control measures or material control (see 4.2.2). CEN/TC 221 Shop fabricated metallic tanks

and equipment for storage tanks and for service stations
SC 1 Tanks Underground tanks (EN 12285-1) Aboveground tanks (EN 12285-2)

SC 2 Equipment Leak detection systems (EN 13160-1 to -7) Overfill prevention devices (EN 13616) Tank contents gauges (EN 13352) Petrol filling stations (EN 13617-1 to -4, EN 13012, EN 14125)

EN 12285-2:2005 (E) 6 1 Scope This document specifies the requirements for metallic shop fabricated cylindrical, horizontal steel tanks, single and double skin for the aboveground storage of water polluting liquids (both flammable and non-flammable) within the following limits:  from 800 mm up to 3 000 mm nominal diameter and,  up to a maximum overall length of 6 times the nominal diameter and,  for liquids with a maximum density of up to 1,9 kg/l and,  with an operating pressure (Po) of maximum 1,5 bar (abs.) and,  where double skin tanks with a vacuum leak detection system are used the cinematic viscosity of the stored media shall not exceed 5 × 10-3 m2/s. This document is applicable for normal ambient temperature conditions (- 20 °C to + 50 °C). Where temperatures are outside this range, additional requirements need to be taken into account. This document is not applicable for the storage of liquids having dangerous good classes listed in Table 1 because of the special dangers involved. Table 1 — List of dangerous goods the storage of which are not covered by this document UN-classification Storage media Class 1 Class 4.2 Class 4.3 Class 5.2 Class 6.2 Class 7 Explosives Substances liable to spontaneous combustion Substances which in contact with water emit flammable gases Organic peroxides Infectious substances Radioactive material, hydrocyanic or hydrocyanic solvent liquids, metalcarbonyls, hydrofluoracid, bromide liquids

NOTE The classifications referred to are those adopted by the United Nations Committee of Experts on the Transport of Dangerous Goods (not to be interpreted as tank classes described in 3.1.4). This document does not cover the installation of tanks which might be subject to local regulations involving pollution control.

EN 12285-2:2005 (E) 7 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 287-1, Qualification test of welders — Fusion welding — Part 1: Steels EN 288–2, Specification and approval of welding procedures for metallic materials — Part 2: Welding procedures specification for arc welding EN 10025-2, Hot rolled products of structural steels - Part 2: Technical delivery conditions for non-alloy structural steels EN 10051:1991 + A1:1997, Continuously hot-rolled uncoated plate, sheet and strip of non-alloy and alloy steels — Tolerances on dimensions and shape (includes amendment A1:1997) EN 10204:2004, Metallic products — Types of inspection documents EN 12285-1:2003, Workshop fabricated steel tanks — Part 1: Horizontal cylindrical single skin and double skin tanks for the underground storage of flammable and non-flammable water polluting liquids EN 13501-1, Fire classification of construction products and building elements — Part 1: Classification using test data from reaction to fire tests EN ISO 898-1, Mechanical properties of fasteners of carbon steel and alloy steel — Part 1: Bolts, screws and studs (ISO 898-1:1999) EN ISO 15607, Specification and qualification of welding procedures for metallic materials — Part 1: General rules (ISO 15607:2003) EN ISO 15614-1, Specification and qualification of welding procedures for metallic materials — Welding procedure test — Part 1: Arc and gas welding of steels and arc welding of nickel and nickel alloys (ISO 15614-1:2004) 3 Terms, definitions, symbols and abbreviations 3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1.1 tank workshop fabricated cylindrical containment for the storage of liquids. It is made of steel, equipped with dished ends and consists of one or more compartments 3.1.2 aboveground tank tank which is not buried in the ground; (a tank installed in a basement is an aboveground tank) 3.1.3 compartment single storage fluid space within a tank 3.1.4 tank classes as defined in Table 2

EN 12285-2:2005 (E) 8 Table 2 — Tank classes Tank class Description Class A Class B Class C for liquids with density up to 1,1 kg/l for liquids with density up to 1,9 kg/l for liquids with density up to 1,9 kg/l and explosion pressure shockproof under atmospheric conditions (see also 3.1.5)

3.1.5 explosion pressure shockproof tank tank which is designed to withstand an internal explosion without leakage; permanent deformations are permissible. Where the atmospheric pressure is 1 bar the maximum explosion pressure is measured at 10 bar (abs.) 3.1.6 tank type for the purpose of this document two tank types are distinguished: Type S: Single skin Type D: Double skin 3.1.7 operating pressure (Po) pressure inside the tank above the liquid during operating conditions 3.1.8 test pressure (Pt1) pressure to which the tank or compartment is subjected for testing 3.1.9 interstitial test pressure (Pt2) pressure to which the interstitial space between the skins is subjected for testing. It is only applicable for double skin tanks 3.1.10 nominal volume storage capacity for which the tank is sold 3.1.11 actual volume total internal capacity of the tank which is equal to or greater than the nominal volume NOTE The safe working capacity of the tank should normally not exceed 95 % of the nominal volume for mineral oil products. For other liquids the safe working capacity conforms to Equation (1). δ351100+=f

(1) where
f is the percentage of nominal volume (%);
δ is the thermal expansion coefficient of the liquid (K).

EN 12285-2:2005 (E) 9 3.2 Symbols and abbreviations For the purpose of this document, the following symbols apply. Dimensions in mm a Weld thickness b1 Width of the saddle b2 Width of compensation plate d1

External nominal diameter of the tank d2
Inside diameter of the manhole d3

Diameter of the manhole cover e1 Distance between centre of the saddle and the end of the cylindrical part of the tank h1 Length

of the straight flange of the dished end k1 Length of the saddle base kp Pitch circle diameter of manway bolts lc Length of the compartment of a tank without dished ends lo Overall length of the tank lz

Length of the tank without dished ends n1
Distance of the saddle foot to the bottom of the tank r1
Crown radius of dished ends r2
Knuckle radius of dished ends r3

Knuckle radius of the outer dished end s1 Nominal thickness of inner skin and inner dished ends s2 Interstitial space s3 Nominal thickness of outer skin s4 Nominal thickness of outer dished ends s5 Nominal thickness of compartment dished ends s6 Nominal thickness of manhole flange and cover s7 Plate thickness of manhole body

EN 12285-2:2005 (E) 10 α

Angle of the saddle β Angle of the compensation plate γ Incline angle for T-joint welding

Thermal expansion coefficient of the liquid
Key 1 Weld Figure 1 — Example of double skin aboveground tank, symbols

EN 12285-2:2005 (E) 11 4 Requirements 4.1 Designation and purchaser's specification Example for designation: A tank according to this document with a nominal volume of 50 m3 and a nominal diameter d1 = 2 500 mm, tank class B and type D Tank EN 12285-2/50/2500/B/D

In addition to the above details the manufacturer shall obtain from the purchaser the following requirements: a) number of compartments and their volumes; b) material specification or liquid to be stored; c) kind of internal and/or external coating, if relevant. 4.2 Materials 4.2.1 General The manufacturer shall select the tank material in accordance with the purchaser's specific requirements or provide information with the tank concerning the suitability of the tank material for the storage media (e.g. by reference to EN 12285-1:2003, Annex B). 4.2.2 Materials for shell, dished ends and manholes Steel according to EN 10025-2, EN 10028-2, EN 10028-7 or EN 10088-1 may be used if the mechanical properties are at least equal to those of S 235 JR according to EN 10025-2. In cases where low temperatures have to be considered (below - 20 °C) at least steel grade S 235 J2G3 according to EN 10025-2 or equal shall be used and in this case wall-thicknesses shall be 6 mm minimum. 4.2.3 Materials for tank fittings Materials used for the fabrication of tank fittings if welded to the tank shall be compatible with the tank material. 4.2.4 Consumables All welding rods/wires and other consumables shall be compatible with the basic material. 4.2.5 Material inspection documentation Material inspection documents for shell plates and dished ends made of carbon steel according to EN 10025-2 shall be in accordance with 3.2 of EN 10204:2004 (Test report “type 2.2”), for all other steel qualities they shall be in accor-dance with 4.1 of EN 10204:2004 (Inspection certificate 3.1 “type 3.1”).

EN 12285-2:2005 (E) 12 4.3 Design 4.3.1 Forms of construction Tanks shall be manufactured by using shell plates and dished ends. 4.3.2 Single skin tanks Single skin tanks shall form an impermeable containment; they also constitute the inner skin of a double skin tank. 4.3.3 Double skin tanks For double skin tanks, an outer skin is welded around the inner tank, which forms an impermeable self contained tank. The outer skin shall cover at least 95 % of the nominal volume of the inner tank. There shall be at least two sockets for the leak detection system and these shall be located at the highest point of the interstitial space. The interstitial space shall be connected to a leak detection system in order to permanently monitor the integrity of the tank. For leak detection systems see EN 13160-1 to -7. Double wall tanks designed for use with a pressure leak detection system shall have stiffening rings in accordance with 7.12 of EN 12285-1:2003 or alternative designs which shall have no lesser performance. 4.3.4 Dished ends Dished ends shall be used for external ends of tanks and to separate compartments. The following dimensions shall apply: 11dr≤ 30/12dr≥ 4.3.5 Compartments The nominal wall thickness of dished ends separating the compartments (compartment dished ends) are given in Table 3. For classes A an B a different form of dished ends separating the compartments is possible, where 11dr=, but without knuckle radius r2 and without straight flange. A compartment dished end with a knuckle radius and a straight flange is equivalent to a reinforcement ring at the same position. 4.3.6 Dimensions 4.3.6.1 Material thickness The nominal wall thickness of inner tank shell, outer tank shell and dished ends shall be declared by the manufacturer in rounded millimetres, and shall be at least as given in Table 3.

EN 12285-2:2005 (E) 13 Table 3 — Nominal wall thickness for inner and outer skin tanks, dished ends and compartment dished end Dimensions in millimetresTank classes Class A Class B Class C Nominal shell thickness a Nominal diameter of the tank d1 s1 inner skin s3 outer skin s1 inner skin s3 outer skin s1 inner skin s3 outer skin 800 up to 1 600 5 3 5 3 5 3 1 601 up to 2 000 6 3 6 3 6 3 2 001 up to 2 500 6 4 7 4 7 4 2 501 up to 3 000 7 4 9 4 9 4 Nominal wall thickness of dished ends Nominal diameter of the tank d1 s1 inner skin s3 outer skin s1 inner skin s3 outer skin s1 inner skin s3 outer skin 800 up to 1 600 5 3 5 3 5 3 1 601 up to 2 000 6 3 6 3 6 3 2 001 up to 2 500 6 5 7 5 7 5 2 501 up to 3 000 7 5 9 5 9 5 Nominal wall thickness of compartment dished ends Nominal diameter of the tank d1 s5

800 up to 1 600 5
1 601 up to 2 000 6
2 001 up to 2 500 6
2 501 up to 3 000 7
a If loose saddles are used see also Table 7.

4.3.6.2 Outer skin 4.3.6.2.1 Circumferential angle The outer skin shall enclose at least 300° of the circumference of the tank, leaving not more than 60° on the top uncovered. In cases where the manhole diameter exceeds d1/2, the manhole shall be provided with an outer skin. 4.3.6.2.2 Interstitial space The interstitial space gap should be as small as practically possible but suitable for the leak detection system to function.

EN 12285-2:2005 (E) 14 4.4 Tolerances 4.4.1 The overall length of the inner tank The tolerance on the overall length of the tank shall be ± 1 % of the real length stated by the manufacturer. 4.4.2 Wall thickness The minimum thickness of dished ends after forming shall be at least 92 % of the nominal wall thickness as given in Table 3. Shell plate thickness shall conform to EN 10051:1991+A1:1997, Table 2. 4.4.3 Circumference of dished ends For the dished ends, the tolerances shall be 06+ mm for d1 ≤ 2 000 mm, and 010+ mm for d1 > 2 000 mm based on the calculated circumference of d1. 4.5 Shell plate arrangement Cross seams shall not be allowed. Longitudinal welds shall not be allowed in the bottom half of the tank. Shell plate joints shall be offset, having a minimum distance e of five times the wall thickness but not less than 25 mm.

Key e Minimum distance Figure 2 — Shell plate arrangement for inner and outer skin 4.6 Manholes and inspection covers Unless otherwise specified by the purchaser, the tanks shall be equipped with at least one inspection cover per compartment. In cases where inspection covers are not allowed, the tanks shall have one manhole of at least d2 = 600 mm and no part of a compartment shall be more than 10 m from a manhole. Single skin tanks shall always have a manhole. The manufacturer shall decide whether manholes (inspection covers, nozzles) shall be of set-through or set-on-type. Nozzles and flanges shall either be welded inside and outside, or by full penetration. For the dimensions of the manholes and its components see Table 4. Gaskets shall be provided and suitable for their purpose.

EN 12285-2:2005 (E) 15 Table 4 — Dimensions of manhole components

Bolts Inside diameter d2 mm Plate thick-ness of manhole body s7 mm Diameter of cover d3 mm Pitch circle diameter kp mm Bolt hole diameter

mm Flange thickness and cover thickness s6 mm Thread size
Number
Class A
Class B and C
600 a 6 720 680 12 16 32 800 7 920 880 12 20 44 1 000 b 7 1 120 1 080
18 -- 20
M 16

48 a If a manhole is required and no specification is given by the purchaser this diameter shall be used. b For tanks of Class C inside diameters of the manhole (d2) exceeding 800 mm are not permitted.

Instead of the manhole covers shown in the Figure 3 and dimensioned in Table 4, ribbed or embossed covers may be used in Class A-tanks with a plate thickness at least equal to the thickness of the inner tank s1. A ribbed or embossed cover shall withstand the test pressure Pt1 (see Table 9). Inspection openings shall only be used for tanks of Class A with d1 ≤ 1 250 mm and tanks of Classes B and C with d1 ≤ 1 000 mm. The diameter of the inspection cover shall not be larger than 300 mm and not smaller than

120 mm, and the thickness of the inspection cover shall be equal to the minimum thickness of the inner tank.

Dimensions in millimetres

Key 1 Gasket 2 Set-on nozzle 3 Set-through nozzle 4 Vent or other pressure relief device Figure 3 — Examples for manholes

EN 12285-2:2005 (E) 16 4.7 Structural bolts Bolts used shall be in accordance with EN ISO 898-1, with a property Class being at least 4.6. The material chosen shall be compatible with the tank material. 4.8 Tank fittings, pipes and nozzles Tank fittings, pipes and nozzles, for double wall

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