Certain products, such as esters (acetates, phthalates, etc) and chlorinated or brominated materials, can react with water and form acidic compounds.
These products are suitable for storage in coated tanks when dry. Such products must have a maximum water content of 0.02 % (200 ppm), be free from acids and stored in completely dry tanks. Subsequent water contamination must be avoided. Water washing of the tank is only acceptable after full recovery of the coating and should be avoided wherever possible.
These products may cause some discoloration of the coating. These products are variable in composition, depending on source, and consequently the effects on the coating can also differ. Subsequent cleaning of the tanks may be difficult so that contamination of the subsequent products may occur.
Vegetable and animal oil, fats, greases and waxes are esters of polyols with fatty acids and nearly always contain free fatty acid. If in contact with water at higher temperatures these esters can saponify, resulting in increased free fatty acid content. Free fatty acids, especially the short chain types, can be very aggressive to tank coatings. Thus, during loading, storage and discharge the acid values should not exceed the maximum values indicated in the table.
Maximum Acid Value (acc.to ISO 660 (1996))
Approximate Percentage Free Fatty Acid
Up to 100 %
SigmaGuard CSF 650
PhenGuard 930/ 935/ 940
Up to 100 %
This acid value according to ISO 660 (1996) is the only accepted method to determine a cargo’s suitability for storage. The free fatty acid percentages given are a guide as the acid value is dependant on the molecular weight of the Fatty Acid(s). The fatty acids (including fatty acid distillates and acid oils) accepted in this list can be stored provided they comply with the following criteria:
- The water content must be limited to 1.0 percent maximum;
- No free mineral acid content is permitted.
The aggressive products can only be stored when the coating is post cured or hot cured.
A post cure can be obtained by:
- A storage period of 3 months with non-aggressive products (without notes 4, 7, 8, or 11) or empty storage tank;
- For insulated tanks full cure will also be obtained after storage of a hot product such as lubricating oil at temperatures of 60 °C (140 °F) for 5 days, or 50 °C (122 °F) for 10 days;
- For non-insulated tanks and outside air temperatures below 15 °C (59 °F), the product temperature should be raised to 80-90 °C (176-194 °F). This can also be achieved by storage of lube oils or mineral oils.
For storage of methanol and vinyl acetate monomer (VAM) in PhenGuard coated storage tanks, a hot cure is required and cannot be substituted by a storage period of 3 months with non-aggressive products. For a hot cure it must be ensured that the entire coated surface has attained the minimum specified temperature and time requirements.
After storage of note 4 marked products, the coating has to be restored to its original condition. This will be obtained by ventilating the tank thoroughly until the tank is gas-free, followed by storage of non-aggressive products
(without notes 4,7,8 or 11) for a period of at least 10 days.
Note 5 Products in this class are proprietary materials and can be stored, provided that the pH is within the range 5.5 to 9.
The tank coating is resistant to the cargo as specified. However the stability of the cargo may be adversely affected and therefore carriage of this cargo should not exceed 90 days. Prior to loading of this product, the tank should be suitably cleaned and the level of inhibitor present in the cargo should be checked to ensure compliance with the requirements of the cargo.
Note 7 Storage of this product should not exceed 30 days and therefore storage for longer periods is not possible. Before another product which notes 4, 7, 8, and 11 is stored; the coating has to be restored to its original condition. This will be obtained by ventilating the tank thoroughly until the tank is in a gas-free condition, followed by storage of non-aggressive products (without notes 4, 7, 8 or 11) for a period of at least 10 days.
Storage of this product should not exceed 90 days and therefore storage for longer periods is not possible. Before another product which notes 4, 7, 8 or 11 is stored; the coating has to be restored to its original condition. This will be obtained by ventilating the tank thoroughly until the tank is in a gas-free condition, by storage of non-aggressive products (without note 4, 7, 8, and 11) for a period of at least 10 days.
Note 9 Lubricating oil, excluding chlorinated, brominated, phosphated and ester types may be stored at temperatures up to 70 °C (158 °F) or 80 °C (176 °F) for loading or discharge only. It is necessary to establish that lubricating oils are not among the product types listed as exclusions.
Note 10 Molasses can be stored when the pH of the product is between 4 and 11. After tank cleaning diluted solutions of molasses should be removed within 24 hours or, when acidic, should be neutralized by an alkaline tank cleaning product to a pH between 5 and 9.
Before loading these aggressive cargoes it is essential that the tank is dry and free of moisture. After storage of these products, the tank should not be brought in contact with water. No steam, water, or aqueous products must come into contact with the coating before its original coating condition is restored. This may be obtained by ventilating the tank thoroughly with dry air (relative humidity lower than 80 %) until the tank is in a gas-free condition. After ventilation, non-aggressive (without notes 4, 7, 8 or 11) and non aqueous products (maximum water content 1 %) can be stored for a period of at least 10 days. An empty tank (dry air) is also acceptable.
Methanol or ethanol products must be pure (contamination with acetaldehyde, formaldehyde, formic acid, acetone and acetic acid should be below 100 ppm per contaminant). The pH of ethanol should be between 4 and 7. Methanol should be completely ‘water free’ (maximum permissible water 0.10 % or 1000 ppm).
Samples of methanol or ethanol must be taken prior to both loading and discharge. The samples must be sealed, properly marked and dated and retained for a minimum of 6 months after discharge of the methanol or ethanol product.
These amines can be stored when free from moisture. If water is present, the alkalinity may increase to a pH higher then 10. The maximum water content is 0.05% (500 ppm). To prevent contamination by water, both the product and the tank must be completely dry at the time of loading and the product should preferably be stored under a dry nitrogen gas-blanket.
Note 13 When full cured according to the times specified in the datasheet is reached, SigmaGuard 750 is resistant to phenols and cresols. However, the tanks must be water cleaned at least once before storing these products.
Crude oils and other crude derivative products can normally be stored in SigmaGuard 750 coated tanks. However, some crude oils/derivative products contain acids and are thus aggressive to zinc silicates, especially when heated and in the presence of water. Cargoes with a neutralisation number above 0.4 (ASTM D664) are not permitted. The pH of water present in these crude products should not be outside the range of 5.5 to 9.
These products can be stored only in completely dry tanks without any water contamination. Maximum water content of the product should be 0.015% (150 ppm).
This is a generic name. Most of these products can be stored but it should be established that no notes are included under the specific type name of such a product elsewhere in the list.
If SigmaGuard 750 coated tanks are also available, it is recommended that they should be used to store this product.
Storage of this product should not exceed 90 days and therefore storage for long periods is not possible. Before storage of another water (containing) product, the coating has to be restored to its original condition. This may be obtained by ventilating the tank thoroughly until the tank is in a gas-free condition, followed by storage of non-aggressive products (without note 4, 7, 8, and 11) or empty (dry air) for a period of at least 10 days. The service life of coatings, when loading aggressive products, can be extended by avoiding the storage of aqueous products.
Automotive gasolines can vary widely in composition.
Addition of considerable amounts of aromatic and/or oxygenated solvents are common. When these cargoes have to be transported the tank coating should be fully cured.
Limits for oxygenated solvents (in volume) as set out in European Directive 2003/17/EC.
(1) Except for unleaded petrol regular (minimum motor octane number (MON) of 81 and a minimum research octane number (RON) of 91) for which the maximum olefin content shall be 21% v/v. These limits shall not preclude the introduction on to the market of a Member State of another unleaded petrol with lower octane numbers than set out in this Annex.
(2) Other mono-alcohols with a final distillation point no higher than the final distillation point laid down in national specifications or, where these do not exist, in industrial specifications for motor fuels.
Blending of automotive gasolines with above mentioned additives in the tank are not acceptable.
For products added but not mentioned in this note, PPG PMC must be contacted before storage of these cargoes.
The information provided in this resistance list is to the best of
our knowledge correct and given in good faith. It is not intended to
be exhaustive and the list of cargoes is subject to change without
notice. The data is liable to modification, based upon experience
and our policy of continued product development. The advice
provided, as guidance only, is based upon laboratory testing and
user reports that are believed to be reliable. As many cargoes can
be variable in composition and we have no control over the use of
our products in service conditions, we accept no responsibility for
the performance of the product or any loss or damage whatsoever,
arising out of such use.
No rights can be derived from the content of this publication.
Unless otherwise agreed in writing, all products and technical
advice given are subject to our standard conditions of sale