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CIRCULAR LETTER

HEMPEL Fire Protection Support

Group R&D

Date: 30 May 2014

TO: Technical Service, Protective Sales

Copy: R&D – Fire Protection, Anton de Castro, Martin Boegsted

Ref. No.: evsc405271

SUBJECT: Revision of Dry-to-handle times of HEMPACORE ONE

Executive summary: Based on field experience and new laboratory test data, the Application Instructions of HEMPACORE ONE 43600 and HEMPACORE ONE FD 43601 have been updated with changes in the Dry-to-handle times, recommended film build up and over-coating times for high DFT’s and handling procedures in order to minimise damages of the intumescent system during handling and transportation. The following recommendations contain even more detailed information about the best practices for Hempacore applications. Hempacore ONE 43600 and Hempacore ONE FD 43601 carry approval for fire protection of structural steel, including 30, 60, 90 and 120 min fire protection. For up to 90 min fire protection of open profiles (I- or H sections) the required Dry Film Thickness (DFT) for the product does not generally exceed 3000µm. For closed profiles (hollow sections) and 120 min open profiles the required DFT can reach till approximately 5500 µm. In all cases, the exact required DFT is depending the massivity (Hp/A) of the relevant steel sections. High thicknesses will require multiple coat applications. Hempacore ONE 43600 can be applied up to 1500 µm DFT per coat. Hempacore ONE FD 43601 can be applied at 1100 µm per coat. This allows completion of application with minimum labour. However, for specifications where the total DFT is above 3000 µm DFT, drying times are significantly extended due to the slower evaporation of the solvent retained in underlying layers and solvent strike back. In such cases a dry film thickness built up in thinner coats will reduce the overall drying time. A distinguish shall be made for in shop (off-site) and (after erection) on-site applications. For in shop applications often it is important that the handling of sections can be done quickly after completion of the spray job. The fastest drying of the coating system is generally desired. For on-site applications it is normally desirable to have minimum amount of coats to minimise the labour, and fast drying time is generally of lower importance since handling of sections after the application is normally not an issue. For on-site applications the high thickness per coat is valuable.

CIRCULAR LETTERS are available on Hempel’s Intranet: Product Portal / Instructions / Circular Letters

Drying studies have been done at Hempel’s laboratories under controlled conditions. These test results are the basis for the drying times mentioned in the application instructions. Drying times of Hempacore ONE 43600 / FD 43601 are dependent on temperature, ventilation, amount of air refreshment, air movement, state of the dryness of previously applied coats, etc. Hence, the provided values shall only be used as a guideline and the actual drying condition should be verified in the actual application site under the real conditions. It is recommended always to check the actual DFT and to make quick indicative measurements for drying before you start with the application of a next coat of Hempacore. By pressing firm with your thumb, the coating shall not be easily indented. If it is possible to make an indent with your thumb without making much effort, it is not recommended to apply the next coat yet, but to leave the coating to dry for a longer time and to postpone the application of the next intumescent coat. If no indention can be made the coating is ready to accept a next coat. In order to obtain the optimum drying of Hempacore ONE at high DFTs, say above 3000µm (DFT), we recommend the following: • Spray 750µm DFT (1000µm WFT) per coat • Leave each coating to dry for approximately 24 hours • Control and monitor the WFT and DFT applied • Use the before mentioned indicative drying test with the thumb to decide if the coating is

ready to accept next coat. Alternatively, long recoat times could be used to speed up the final drying, e.g. • Spray 1500µm DFT (2000µm WFT) Hempacore ONE 43600. For Hempacore ONE FD 43601

the max DFT is 1100µm (approx. 1450µm WFT). • Leave the coating to dry for approximately 48 hours • Control and monitor the WFT and DFT applied • Again, use the before mentioned indicative drying test with the thumb. As an intermediate solution the application of high DFTs can be build up as • Spray the first two coats of Hempacore ONE 43600 at 1500µm DFT (2000µm WFT) • Spray the remaining coats at 750µm DFT (1000µm WFT) • Leave each coating to dry for minimum 24 hours • Control and monitor the WFT and DFT applied • Use the before mentioned indicative drying test with the thumb. The throughput for the total coating system will be faster when longer recoat time is used in between the application of two coats of Hempacore. At areas where spray applications have overlapped, the DFT may be way higher as the average DFT. As the speed of drying is directly related to the DFT of the coating, the drying of the complete coat will depend the thickest areas. In case the practices mentioned in this document are not respected, and the appearance of a coating system is very soft, the only possible means to improve hardness is time. During time the solvent will slowly evaporate and hardness will develop. For a 5000µm DFT coating this may take very long time. Times up to 1½ - 2 months have been measured, before acceptable hardness was achieved. When applications have been made at higher DFTs as 1500µm per coat, this time is even significantly prolonged further. Before application of a topcoat the Hempacore product shall be dry hard, except when an approved acrylic topcoat is used. For the most speedy in-shop times it can be sometimes a solution to apply the topcoat on-site, or use acrylic topcoats.

CIRCULAR LETTERS are available on Hempel’s Intranet: Product Portal / Instructions / Circular Letters

After drying of the coating system, off-site applied the steel sections will need to be handled. It is important to address that due to the thermoplastic nature of acrylic intumescent coatings, they are sensitive to damage, also after full drying. Generally it is more of a matter to minimise the damage as to prevent damage. Therefore special care should be taken to smartly handle the coated steel sections. If the steel sections have areas that are not sprayed with intumescent paint (e.g. areas left blank as welding/botling area), the lifting straps should be installed in those places when possible. This reduces the amount of damage, and therefore also the required repair. The amount of supporting beams normally of wood, shall be limited to the minimum required, in order to minimise the damaged areas. Areas where the sections lean on the supporting beams are likely to be damaged Maintain sufficient ventilation, also when the product is considered dry. Therefore, do not cover up the sections as this will affect the final drying properties. For any questions, please contact Fire Protection Support (FireProtection.Support@hempel.com) Erik van Schaijk Research Engineer Group R&D – Fire Protection Polinyà (Barcelona)