Workshop Floating Roof Seals

IMHOFTank-Technik

WORKSHOP Floating Roof Seals

IMHOFWORKSHOP Floating Roof Sealspage 1

Tank-Technik

Contents1. 1.1 1.2 2. 3. General problems of hydrocarbon liquid storage Critical data of hydrocarbon vapours General advantages of floating roof tanks versus fixed roof tanks for liquids with high vapour pressure Tank types and floating roof types Codes of tank construction 4. 5. 5.1 5.2 6. 6.1 6.2 6.3 API 650 BS 2654, substituted by EN 14015 DIN 4119, substituted by EN 14015 EC Germany Switzerland USA

National and public codes of hydrocarbon emission control

Historical development of tank construction and emission control Tanks with passive emission control Tanks with active emission control Determination of hydrocarbon emission and definition of floating roof efficiency Calculation methods of API-Manual of Petroleum Measurement Standards, Chapter 19, Section 1 and 2 Definition of floating roof efficiency Floating roof efficiency

6.3.1 Efficiencies attainable of external floating roof tanks, depending on turnover rate and tank diameter 6.3.2 Efficiencies attainable of internal floating roof tanks, depending on turnover rate and tank diameter 6.4. 6.5. 7. 8. 9. 10. 11. 12. 13. 14. 15. Emission rates per year and meter of rim space Evaluation of emission by practical tests at TAMAG/Switzerland Limits of floating roof technology Possible future improvements of passive emission control Risks of tank geometry and rim space tolerances Centring of floating roof Standard requirements for floating roof seals Design criteria of floating roof seals (EN 14015) Highlights of IMHOF seals Reduction of emission and costs involved Sealing membrane materials

Status: 02/2005

RS/22.02.05 Workshop komplett.doc


Tank-Technik

1.

General Problems of Hydrocarbon Liquid Storage

1.1 Critical Data of Hydrocarbon VapoursApproximate Vapour Pressure at 20C [mbar] Pentane Gasoline Crude Oil Hexane Methanol Benzene Ethanol Heptane Jet Fuel Heating Oil 560 400 400 170 125 100 60 50 3 0,5 Limits of Explosive Vapour Concentration [% Volume] ~ 1,3 8,0 ~ 1,0 7,5 ~ 0,7 5,0 ~ 1,2 7,4 ~ 5,5 26,5 ~ 1,2 8,0 ~ 3,5 15,5 ~ 1,0 6,7 ~ 0,7 5,0 ~ 0,6 6,5 42 - 72 55 < - 20 11 < - 11 12 240 455 555 425 215 257 220 < - 20 Flash Point [C] Temperature of Vapour Ignition [C] 285 240 - 280

1.2 General Advantages of Floating Roof Tanks versus Fixed Roof Tanks for Liquids with high Vapour Pressure No filling losses No breathing losses (daily) No risks of tank explosion or tank implosion Effective protection against lightning strikes and tank fires Effective cooling of storage product No problems of fixed roof corrosion No need for costly vapour balancing and vapour treatment systems



Tank-Technik

2.

Tank Types and Floating Roof Types

Floating roof tanks with ring pontoon for diameters > 12 m and < 70 m (EFRT)

Floating roof tanks with double deck for diameters < 12 m and > 70 m (EFRT)

Fixed roof tanks with roof column (IFRT)

Fixed roof tanks without roof column (IFRT)

3.

Codes of Tank Construction

In the past large aboveground hydrocarbon storage tanks in Europe and in the world were built according to national codes, more or less identical to the American tank code API 650 (BS 2654, DIN 4119, etc.). Since several years a new European tank standard is worked out, named EN 14015: Specification for the design and manufacture of site built, vertical, cylindrical, flat-bottomed, above ground, welded, metallic tanks for the storage of liquids at ambient temperatures and above. The new European tank standard is more detailed and precise as API 650 and takes better note to European steel qualities, quality control and environmental and safety regulations in Europe.



Tank-Technik

4. EC

National and Public Codes of Hydrocarbon Emission Control

94/63 EC: Since 1995 all EC countries are to follow the rules of directive 94/63/EC for storage and distribution of motor gasoline. The following efficiency factors for EFRT and IFRT are to be met, in comparison to a fixed roof tank with the same yearly turnover, having a vacuum/pressure valve but no internal floating cover. a) Tank existing before 31.12.1995 EFRT: 95% efficiency IFRT: 90% efficiency EFRT: External Floating Roof Tank IFRT: Internal Floating Roof Tank

b)

Tanks built after 31.12.1995 EFRT: 95% efficiency by using primary and secondary seals IFRT: 95% efficiency by using primary and secondary seals

The efficiency factors can be calculated by using Chapter 19, Section 1 and Section 2 of APIs Evaporation Loss Measurement Standards. IPPC: The European Directive 96/61/EC asks for Integrated Pollution Prevention and Control (IPPC). Technical work groups of the EC member states worked out a BREF document on BAT (Best Available Technique) and describes Emission Control Measures (ECM).

GERMANYBesides the above EC codes for storage and distribution of gasoline, for all other storage tanks in tank farms and refineries, Germany uses its rules of TA-Luft 2002. Here efficiencies of floating roof systems (external or internal) shall be better than 97 %, when storing products with vapor pressures above 13 mbar at 20 C.

SWITZERLANDThe Swiss health agency (Lufthygieneamt) has specified the most stringent rules of emission control in Europe. For any size of tank farm in Switzerland the emission of hydrocarbons shall stay below a maximum of 3 kg/hr, or alternatively the maximum hydrocarbon concentration emitting to the atmosphere shall stay below 150 mg/m.

USAAt present there is no uniform federal program which regulates aboveground storage tanks. Instead, there is a complex, confusing, and overlapping network of miscellaneous federal statutes and regulations that directly or indirectly govern tanks as well as local requirements imposed by state and local authorities. (Philip E. Myers, Aboveground Storage Tanks, 1997) According to the Clean Air Act (CAA) all floating roof tanks are to be equipped with primary seal and with secondary seal. For fixed roof tanks with internal floating cover the regulations ask for liquid mounted single seals, like a shoe type seal, or a vapour mounted primary seal with secondary seal. The US regulations also specify the sealing requirements for guide poles, sample wells and other fittings of the floating roof. Seal gaps at floating roof tanks are to be measured once per year. For internal floating covers a yearly visual inspection of seals is required.



Tank-Technik

5.

Historical Development of Tank Construction and Emission Control for Hydrocarbon Storage Tanks

The emission rates and efficiencies stated below are given for the following example: Tank : 30 m Tank height: 13 m 3 Tank volume: 8730 m 12 Turnovers/year gasoline 600 mbar RVP M = 64 g/mol Tank colour: white tm vm pm = 10 C = 3,0 m/s = 1013 mbar

5.1 Tanks with Passive Emission Control

Fixed Roof Tank with P/V Valve

~ 1920e = 86.815 kg/year =0%tank

Base Case of EC Directive 94/63

~ 1925e = 9.665 kg/year = 88,9 %tank

Floating Roof Tank with Shoe Type Primary Seal only

~1960e = 1.625 kg/year = 98,1 %tank

Fixed Roof Tank with free vents, Internal Floating Cover as Steel Pan with Single Foam Filled Seal

~ 1990e = 914 kg/year = 99,0 %tank

Floating Roof Tank with Double Seal (rim mounted) Guide Pole Seal Roof Leg Seals



Tank-Technik

5.2 Tanks with Active Emission Control

~1990e 100-500 kg/year 99,4-99,9 %total

Fixed Roof Tank with Vapour Balancing System, Gasholder, Multistage Vapour Recovery Unit ( = 99,985%)

2004e < 100 kg/year > 99,9 %total

Floating Roof Tank with Multifold Seal, Vapour Draw-Off System, Single Stage Vapour Recovery Unit ( = 97 %)

Rsum:Tanks or tank systems subject to active emission control measures often apply vapour balancing systems, gasholders and vapour recovery units. Residual emission is given by all flange connections, the function of safety valves, gasholder systems with huge rubber membranes, and the efficiency of the vapour recovery unit. Depending on the details of equipment, the total efficiency of such systems can vary between approximately 99,4 and 99,9 %, based on the application of a multistage vapour recovery system with efficiencies of 99,85 %. Alternatively floating roof tanks with multifold sealing systems and vapour draw-off lines can be run with small and constant vapour quantities, requiring small and single stage recovery units only. The total investment and the power consumption required leads to much higher costs for the alternative with vapour balancing systems and without floating roof technology. Furthermore the installation of additional equipment and the extra power consumption creates quantities of substitute emissions of CO2, CO, SO2, NOX, dust, cooling water, in power stations, steel mills and other plants of raw material supply. Hence the total balance of emissions for systems using vapour balancing and vapour recovery units in relation to systems with floating roofs is negative. The big breathing volumes of fixed roof tanks (and gasholders) with high vapour concentrations do not lead to economical and ecological sound solutions.



Tank-Technik

6.

Determination of Hydrocarbon Emission and Definition of Floating Roof Efficiency

6.1 Calculation Method of API-Manual of Petroleum Measurement Standards, Chapter 19, Section 1 and Section 2

Emission Formerly calculated with API 2518

Now calculated with Chapter 19 Section 1



Now calculated with Chapter 19 Section 2, Edition April 1997

6.2 Definition of Floating Roof EfficiencyThe efficiency of a floating roof tank (external or internal) is defined as relation of emissions between the floating roof tank in question and a fixed roof tank, equipped with pressure / vacuum valve only, having the same tank dimensions (diameter, height, volume) and the same yearly throughput with the same storage product as in the floating roof tank.



Tank-Technik

6.3 Floating Roof Efficiency 6.3.1 Efficiencies attainable of External Floating Roof Tanks, depending on Turnover Rate and Tank Diameter

Calculation of efficiency according to API-Manual of Petroleum Measurement Standards Chapter 19, Sec. 1 and Sec. 2 (April 1997)

100

storage conditions: product: gasoline Reid vapor pressure: 600 mbar average wind speed: 3,0 m/s daily average ambient temperature: 10,0 C

798

6 5

4 3 2 1

96

1 294efficiency of EFRT [%]

D= 12,0 m; V= 1075 m; H= 10,0 m D= 15,0 m; V= 1847 m; H= 11,0 m D= 20,0 m; V= 3581 m; H= 12,0 m D= 30,0 m; V= 8730 m; H= 13,0 m D= 40,0 m; V= 16713 m; H= 14,0 m D= 50,0 m; V= 27980 m; H= 15,0 m D= 60,0 m; V= 42977 m; H= 16,0 m

3 4 590

92

6 788

86

All EFRT are equipped with shoe type primary seal plus rim-mounted secondary seal plus guidepole seal and roof leg seals.

84 0 10 20 30number of filling actions per yearRS/22.02.05 Workshop komplett.doc


Tank-Technik

6.3.2 Efficiencies attainable of Internal Floating Roof Tanks, depending on Turnover Rate and Tank DiameterCalculation of efficiency according to API-Manual of Petroleum Measurement Standards Chapter 19, Sec. 1 and Sec. 2 (April 1997)

100

5 4 3 2

storage conditions: gasoline product: Reid vapor pressure: 600 mbar daily average ambient temperature: 10,0 C

1

98

196

D= 12,0 m; V= 1075 m; H= 10,0 m

2efficiency of IFRT [%]

D= 15,0 m; V= 1847 m; H= 11,0 m

94

3

D= 20,0 m; V= 3581 m; H= 12,0 m

492

D= 30,0 m; V= 8730 m; H= 13,0 m

5

D= 40,0 m; V= 16713 m; H= 14,0 m

90

All IFRT are equipped with shoe type primary seal plus guidepole seal and roof leg seals.

88 0 10 20 30number of filling actions per yearRS/22.02.05 Workshop komplett.doc


Tank-Technik

6.4 Emission rates per year and meter of rim space, given for standard seal types as tested by API

Yearly Emission of Floating Roof Rim Spaces per Meter of Tank Circumference, depending on Type of Seal and Wind Velocity, according API - Manual of Petroleum Measurement Standards Chapter 19, Section 2, April 1997 (Data calculated by IMHOF Tank-Technik)1000,0

7

Storage Product: Gasoline RVP = 600 mbar average stock temperature: T S= 14CThe diagram shows the data for tight-fitting seals. The data for average-fitting seals or damaged seals are higher.Shoe seal primary only (1)

1 8

9100,0 Shoe seal + shoe mounted secondary (2)

2

Shoe seal + rim mounted secondary (3) Liquid mounted primary seal only (4)

4

Liquid mounted primary + weather shield (5) Liquid mounted primary + rim mounted secondary (6) Vapor mounted primary seal only (7) Vapor mounted primary + weather shield (8) Vapor mounted primary + rim mounted secondary (9)

Emission of rim space [kg/m*a]

5 3

10,0

6

1

2

3

1,0

4

5

6

7

8

9

0,1 0,00

2,00

4,00

6,00

8,00

wind velocity [m/s]



Tank-Technik

6.5 Evaluation of Emission by Practical Tests, carried out at TAMAG / SwitzerlandTotal storage capacity of tank farm: 750.000 m3

21 4

Fixed roof tanks; 44,0 m Fixed roof tanks; 19,6 m

All tanks originally had been equipped with pantype, welded internal floating roofs with conventional lip seals only. The roofs are equipped with ventilation openings.

Tank Service : 134 5 3

Tanks; Tanks; Tanks; Tanks;

44,0 19,6 44,0 44,0

m m m m

gasoline 95 and 98 gasoline 95 and 98 heating oil diesel oil

Hydrocarbon emission limit requested by the Swiss Health Agency (Lufthygieneamt) in 1990: max. 3 kg / h for the complete tank farm at any time of the year, or alternatively 3 max. 150 mg / m outlet concentration at any tank.

Alternative Solutions taken in consideration:Alternative 1: Closing of all ventilation openings of tanks, installation of vapour balancing pipework and installation of vapour recovery unit (VRU) costs expected: ~ 20 Mio SFr Alternative 2: Installation of improved sealing systems, and application of additional passive emission control measures like shadowing, insulation, cooling of tanks, etc. costs expected: unknown In view of the high installation and operation costs of alternative 1, TAMAG decided for alternative 2. The necessary emission tests were specified and carried out by EMPA (Eidgenssische Materialprfungsanstalt).



Tank-Technik

Continuation: 6.5 TAMAG / SwitzerlandStep by Step Improvement of Tank System and Test Results:1991 In tank no. 12 ( 44,0 m), used for storage of gasoline 95, the lip-type seal was substituted by a liquidmounted foam seal, type "Slimline" (see Fig. 1). The emission measurement carried out in November showed values close to the allowable maximum but was not acceptable to the authorities due to the low temperature level in November. 1992 Emission measurement at tank no. 12 was carried out in May. During discharge of gasoline hydrocarbon concentration above the floating cover was found between 3 300 and 1500 mg/m being 2 to 10 times higher than acceptable. 1993 Tank no. 8 was equipped with a "Slimeline" foam seal with double foam elements. Tank no. 9 was equipped with a double compression plate seal, type "Double-Flex A". Emission tests were carried out in June and August; storage product was gasoline 95. No significant reduction of emissions was found in relation to the single foam filled primary seal of tank no. 12, tested in 1992. 1994 Tank no. 5 was equipped with a double seal IM-IGT + IM-WSII (see Fig. 1), supplied by IMHOF. First emission tests showed a reduction of emission of approx. 50 % in relation to the tests in 1993. But it was uncertain if this reduction was sufficient at all times of the year. 1995 Tank no. 11 was equipped with a multifold sealing system IM-IGS + IM-WSII (see Fig. 1), supplied by IMHOF. Emission tests were carried out between end of July and mid of August. Short after tank filling the gasoline temperatures reached 25 C and the emission values were above limit. As from beginning of August the gasoline temperatures dropped and the emission stayed well below its limit. In general the emission was approx. 50 % of the values given by the test in 1994. 1996: Emission tests in tanks no. 5, 11 and 12 were carried out in parallel, during May to October. The storage product was gasoline 95, with slight differences in composition: Tank no. Tank no. Tank no. 5 ( 44,0 m): 11 ( 44,0 m): 12 ( 44,0 m): Seal IM-IGT + IM-WSII (supply in 1994) Tank painted grey Seal IM-IGS + IM-WSII (supply in 1995) Tank roof painted white; Tank shell painted grey Seal type "Slimline" (supply in 1991) Tank roof painted white; Tank shell painted grey



Tank-Technik

Continuation: 6.5 TAMAG / SwitzerlandIn May the gas concentrations above the floating Tank no. 5: Tank no. 11: Tank no. 12: cover had been (see Fig. 2): 3 35 mg HC/m 3 20 mg HC/m 3 60 mg HC/m

During July and August the gasoline temperature was well above 20 C and the limits of emission could not be met. The customer decided to repeat this test with the same tanks in 1997 using a water irrigation at the tank roofs. 1997: Emission tests in tanks no. 5, 11 and 12 were carried out in parallel, during May to July. Although the tank roofs were irrigated with pond water 20 C, the gasoline temperatures reached values of 23 C. The emission values were below the values of 1996 but the limit of gas concentration of 150 mg 3 HC/m could not be met at any time during this period. During these tests IMHOF had carried out numerous temperature measurements at tank walls inside and outside the tanks. On the base of these temperature measurements the customer could be convinced that it is necessary to paint the tanks completely white. 1998: Emission tests in tanks no. 5 and 11, were carried out in parallel, during May to September. Due to the fact that all tanks had been painted completely white the maximum temperatures of the storage product stayed below 20 C (see Fig. 3) and the requested maximum emission level of 3 kg/h for the whole tank farm was met. Furthermore in future years the tank farm would store gasolines according to EC-Directive 98/70 with approximately 30 % lower vapour pressures.

Rsum:The stringent limit of a maximum emission of 3 kg/h for the complete tank farm with 25 tanks, as well 3 as the limit for the vapour concentration above the floating cover (150 mg HC/m ), can be met: with direct contact floating cover (steel pan), with multifold periphery seals, with tanks painted white.



Tank-Technik

Continuation: 6.5 TAMAG / Switzerland

Fig. 1:

Seals tested in parallel, 1996 and 1997, at TAMAG / Mellingen

200

160

Limit (equivalent to 150 mgHC/m)

140 120 100

Tank 12 Tank 5 Tank 1105.05.96 07.05.96 09.05.96 11.05.96 13.05.96 15.05.96 17.05.96 19.05.96 21.05.96 23.05.96 25.05.96 27.05.96 29.05.96 31.05.96

80 60 40 20 0

Fig. 2:

Concentrations of gas above the floating cover, may 1996, TAMAG / Mellingen

24

2400

Tank 1122 2000 1600

Gas concentration

Temperature [C]

20 18 16 14 12 10

04. Aug 11. Aug 18. Aug 25. Aug

1200

800

400

0

Date Average temperature of gasoline 1997 (only tank roof white) Average temperature of gasoline 1998 (tank completely white) gas concentration 1997 above floating roof (only tank roof white) gas concentration 1998 above floating roof (tank completely white)

Fig. 3:

Influence of the tank colour (comparison of the emissions measured at tank no. 11 in 1997 and 1998)RS/22.02.05 Workshop komplett.doc

01. Sep

23. Jun

30. Jun

07. Jul

14. Jul

21. Jul

28. Jul

[mgC/m]

Concentration of gas [C/m]

180


Tank-Technik

7.

Limits of Floating Roof Technology

When storing hydrocarbon liquids in vertical tanks with floating roof (EFRT) or floating cover (IFRT) the efficiency of the system floating roof/ floating cover plus seals can always be upgraded with the application of better seals and/or multifold sealing systems.

The expected efficiencies are e.g.: External Floating Roof Tank Primary seal Double seal + guide pole seal Triple seal + guide pole seal = 88 % = 97,5 % = 99,5 % etc. Internal Floating Roof Tank = 95 % = 99 % = 99,8 % etc.

For vertical storage tanks with diameters above approximately 8 m the application of improved sealing technologies, economically as well as ecologically always is the winning decision against systems with vapour balancing and vapour recovery, provided the temperature and the vapour pressure of the liquid stored stays below a certain limit. For gasoline in winter quality having a Reid Vapour Pressure of 90 kPa as used in the past, this limit of temperature was found in practical tests at 19.6 C, with a vapour pressure of 48 kPa. Gasoline according to Euronorm 2000 will reach this vapour pressure at approximately 31 C, which means this temperature will not be reached under normal operating conditions. The above limit was found for a fixed roof tank, 44 m diameter, with pan-type internal floating cover, equipped with a multifold sealing system. We expect this vapour pressure of 48 kPa at storage temperature to be about the limit pressure for other storage products also, when using passive emission control measures only. For hydrocarbon liquids having a vapour pressure higher than approximately 48 kPa at the expected storage temperature of the bulk liquid, active emission control with vapour recovery/ vapour destruction is justified economically and ecologically. But the use of vapour balancing, gasholders and vapour recovery units are not the only answer of active emission control for refinery tanks. In many cases systems with floating roofs/ floating covers in the form of full-contact or steel-welded design, combined with a continuous and small vapour draw-off from the interspace of multifold sealing systems, followed by vapour recovery/ vapour destruction, is the more economical solution and leeds to much higher overall emission control.



Tank-Technik

8.

Possible Future Improvements of Passive Emission Control

Tests on fixed roof tanks with internal floating covers (TAMAG/ Switzerland) have shown a big influence of temporally and locally high tank wall temperatures at areas of high sun radiation. As long as the bulk liquid temperature stays below a certain limit temperature (see TAMAG report) the amount of emission is closely linked to respective tank wall temperatures. This can be explained by some kind of film evaporation at the inner tank wall. All other relevant temperatures (liquid bulk temperature, temperature of floating roof, temperature of vapour space above the floating roof) do not show a big influence on emission quantities. Therefore measures for passive emission control for fixed roof tanks are:

Solid design of internal floating cover using full contact covers, preferably steel-welded, pontoon-type or pan-type Multifold seal with submerged primary seal element Tank paint with high solar heat reflection

insulation

sun shield

and alternatively: Application of sun shields or insulation of tank walls and tank roof

For floating roof tanks the characteristic of the seals (rim seal loss factor), the wind velocity and the vapour pressure (temperature) of the product stored have the highest impact on emission. Hence the measures of passive emission control for floating roof tanks are:

Multifold seals with submerged primary seal element, Tank paint with high solar heat reflectionsun shield

and alternatively: Application of sun shields or insulation of tank walls, respectively tank in tank design Natural cooling of floating roof by evaporation of rain water

rainwater evaporation



Tank-Technik

9.

Risks of Tank Geometry and Rim Space Tolerances

Measurement of Tank DeformationNo tank code in the world, neither API 650, BS 2654; DIN 4119; EN 14015, nor any other tank code dealing with floating roof tanks can guarantee that a certain floating roof tank built in accordance with those standards, and a standard floating roof seal installed will fit together to seal the rim space at all floating conditions. The reason for this unsatisfying situation is that all existing tank codes bypass the realistic definitions of the floating roof system. The point were all tank codes are wrong is the fact that they all talk about the rim space, which means a rim space at any point of the tank circumference. And they talk of deformations of the tank shell and tolerances of the tank radius or tank diameter only. These definitions do not give a complete base for the tolerances a floating roof seal has to deal with. Of course not only the tank shell but also the floating roof has its deformations and deviations against the design geometry. In addition to this the roof can float into any direction. This means all tolerances of two diametrical points of the tank shell and the pontoon can add up at one side of the floating roof only. The technically sound and successful evaluation of existing rim space dimensions to be used for the design of floating roof seals - according to our design criteria - is worked out as follows: a) Add up the rim space measurements of two diametrical rim spaces (A1+A2, B1+B2, C1+C2, etc.) to find the max. total clearance between tank shell and floating roof at the tank circumference. The distance between two measuring points at the tank circumference should not be bigger than approx. 3 m. b) Repeat the above measurement procedure for different heights of flotation.

A1 C2 B1 80 % aromatics and pure Benzene, Toluene, Xylene Gasoline with alcohol, pure alcohol Gasoline with MTBE Pure MTBE Acidic liquids and sea water Ketones, esters, nitro- and chlorinated hydrocarbons NBR PU With abrasion * (e.g. IM-PNS) PU NBR PU ~ 1,0 mm 2-3 mm ~ 1,0 mm --2-3 mm ~ 1,0 mm ------Without abrasion (e.g. IM-PGT) PU NBR PU PTFE PU NBR CSM PU PTFE PU CSM PTFE

**

~ 0,6 mm ~ 1,5 mm ~ 0,6 mm ~ 0,3 mm ~ 1,0 mm ~ 1,5 mm ~ 0,7 mm ~ 0,6 mm ~ 0,3 mm ~ 1,0 mm ~ 0,7 mm ~ 0,3 mm

Recommended membrane materials for Secondary SealsStorage liquid (under ambient temperature) Crude oil, Heating oil, Jet fuel, Diesel, Gasolines with up to 40 % aromatics Gasolines/hydrocarbon with 40 80 % aromatics Hydrocarbons with > 80 % aromatics and pure Benzene, Toluene, Xylene Gasoline with alcohol, pure alcohol Gasoline with MTBE Pure MTBE Acidic liquids and sea water Ketones, esters, nitro- and chlorinated hydrocarbons With abrasion * (e.g. IM-WS2) PU ~ 1,0 mm NBR 2-3 mm CSM + PU PU ~ 1,0 mm NBR 2-3 mm CSM + PU PU ~ 1,0 mm Without abrasion ** (e.g. IM-WSW) CSM ~ 0,7 mm

CSM

~ 0,7 mm

PU CSM CSM CSM CSM CSM

~ 1,0 mm ~ 0,7 mm ~ 0,7 mm ~ 0,7 mm ~ 0,7 mm ~ 0,7 mm

NBR 2-3 mm CSM + PU PU PU NBR NBR ~ 1,0 mm ~ 1,0 mm 2-3 mm 2-3 mm

* with contact of sealing membrane to the tank wall ** without contact of sealing membrane to the tank wallRS/22.02.05 Workshop komplett.doc

Documents

Workshop Floating Roof Seals