Drip pan

Geotextile drip pan around a transformer in the USA.

A drip pan is a safety measure when handling liquid, water-polluting substances . It is intended to catch substances escaping from the system or the storage container (in the event of a fire also extinguishing water ) and thus prevent their release into the ground or water. Collecting trays are liquid-tight components, but not structural facilities or rooms in buildings. In Germany, sumps are mainly made of reinforced concrete , sheet steel and plastic ( PE and GRP ).

Legislation

The need for containment areas is determined by Section 62 of the Water Management Act (WHG) and the related ordinance on systems for handling water-polluting substances (AwSV) (there retention device , Section 2, Paragraph 16 AwSV). Collection trays are a technical variant for providing the required retention volume. If they are to be used for systems for the storage, filling and handling of water-polluting substances, they are subject to the rules of the Construction Products Act. The steel tray guideline (StawaR) is a generally recognized rule regarding the technical building regulations for collecting trays made of steel with a volume of up to 1000 liters. There are no equivalent technical building regulations for plastic sumps (usually made of polyethylene or GRP ), but compliance with the StawaR guidelines is checked for each model by the DIBt and confirmed with the so-called Ü symbol.

Execution of the tubs according to StawaR

The StawaR is listed under No. 15.22 in the building regulations list A Part 1 of the German Institute for Building Technology . It is therefore considered to be an established technical building regulation. Steel drip trays are mainly used in industrial and commercial storage facilities. The most important requirements of the StawaR are:

The tub must be leakproof. It must be resistant to the stored substance and, in the case of rusting steels, have corrosion protection. The minimum wall thickness is 3 mm for steel and 2 mm for stainless steel. Welded constructions are only permitted with proof of suitability from the welder.

The bottom of the tub must be able to be checked for corrosion and is therefore usually not placed directly on the floor (except for flat tubs with reliable corrosion protection or corrosion is excluded, e.g. with stainless steel under conditions of machining).

The tub must generally be over 5 cm high and have a freeboard of 2 cm above the liquid level after it emerges. When covering such tubs with grids, the bottom edge of the grate must be above the possible height of the liquid level.

When bending the material, the bending radius must be larger than the material thickness, otherwise the probability of strain hardening and cracking increases.

Static proof is required for the hydrostatic pressure , for other load cases (other applied forces) a load test with a safety factor of 2.

Proof of conformity

The trays may only be placed on the market if compliance with the requirements has been proven. Evidence is provided in two stages:

Initial test by a recognized test center: For every manufacturer, compliance with the requirements for the drip pan and production must be checked by a test center recognized for this purpose and documented in a test report.
In-house production control: The following tests must be carried out on each collecting tray:
- Construction test for compliance with Section 2.1 (3) to (10) StawaR
- Weld seam inspection (visual inspection)
- Leak test (vacuum process, dye penetration process; ultrasound)
- Check corrosion protection (not applicable for stainless steel)

The resistance to the storage media is not tested as part of the proof of conformity.

Identification of the tubs

Collecting trays must be permanently marked with the following data:

Manufacturer
Year of manufacture and serial number
Material of the tub
Load capacity of the tray or the grate
Collection volume (total volume -2 cm freeboard)
Note "Use according to StawaR"
Ü mark (only with proof of conformity)

Dimensioning in Germany

For the dimensioning of the size of collecting trays, the ordinance on systems for handling substances hazardous to water must be checked. In principle, the volume of the largest container that is stored on the collecting basins is decisive here; however, at least 10% of the total volume of the system must be retained, provided it is not a water protection area . In this case, 100% of the total volume of the system must be retained.

Example 1: If two 60-liter drums are to be stored on a collecting tray, this must have a collecting volume of at least 60 liters (the volume of the largest container is decisive here)
Example 2: If twelve 60-liter drums are to be stored on a collecting tray, this must have a collecting volume of at least 72 liters (the 10% of the total volume is decisive here)
Example 3: Four 60-liter barrels are to be stored in a water protection area, the collecting basin must have a minimum volume of 240 liters (the requirement is that 100% of the total volume is retained)

Dimensioning in Austria

If the storage takes place in single-walled, portable containers, the collecting basin must be able to hold at least 75% of the nominal content of all containers stored in it, but in any case the nominal content of the largest container. If only break-proof, portable containers made of metallic materials are used for storage, the collecting tray must be able to hold at least 50% of the nominal content of all containers stored in it, but in any case the nominal content of the largest container. If only break-proof, manually movable containers made of metallic materials are used for storage, the collecting tray must be able to hold at least 30% of the nominal content of all containers stored in it, but in any case the nominal content of the largest container. When storing in the water protection area, the collection volume must i. d. Usually 100% of the stock amount.

Individual evidence

↑ Until the federal regulations came into force, the ordinances issued in accordance with § 19g WHG old version on systems for handling substances hazardous to water (VAwS) and administrative regulations of the federal states still applied.

↑ Construction Products Act - BauPG

↑ Guideline on the requirements for steel collecting trays with a capacity of up to 1000 liters (StawaR) - July 2005 version (PDF; 40 kB) DIBt-Mitteilungen 3/2006, June 9, 2006, accessed on May 16, 2010 .

↑ Under No. 15 construction products for stationary systems for the storage, filling and handling of water-polluting substances are listed.

↑ cf. Section 17 (2) of the model building regulations .

[1] Until the federal regulations came into force, the ordinances issued in accordance with § 19g WHG old version on systems for handling substances hazardous to water (VAwS) and administrative regulations of the federal states still applied.

[BauPG-2] Construction Products Act - BauPG

[StawaR-3] Guideline on the requirements for steel collecting trays with a capacity of up to 1000 liters (StawaR) - July 2005 version (PDF; 40 kB) DIBt-Mitteilungen 3/2006, June 9, 2006, accessed on May 16, 2010 .

[4] Under No. 15 construction products for stationary systems for the storage, filling and handling of water-polluting substances are listed.

[5] . Section 17 (2) of the model building regulations .