Envelope gaskets can be of a dissipative/conductive design for applications for which a static discharge is necessary and required. For this purpose, it is possible to realise the discharge using an electrically conductive PTFE-envelope made from Dyneon™ TFM™ 6221 WS 7221 and/or using an grounding tab/ grounding wire which is fitted to the outer diameter of the corrugated ring. The discharge of the electrical load is ensured via glass lined pipes, metal reinforcement and fan-type lock washers. The retaining brackets can also be fitted to the corrugated ring as assembly and centring aids.
GROUNDING AND EQUIPOTENTIAL BONDING IN PIPES WITH INSULATING
The grounding of a plant can be obstructed by insulating com- ponents such as gaskets or insulating operating materials like greases. The remaining conductive components have to be connected to each other and grounded when using insulating materials such as spacers made from plastic with high resistance. Alternatively, it is possible to ground every plant part individually. In this environment it is particularly important to consider parts which are not visible from the outside, such as: Ball valves with insulating gaskets or also metal inserts in gaskets.
It depends on the specific conditions if equipotential bonding is necessary for pipelines and gaskets:
Insulating coating on the inside
Insulating coating on the outside
Gasket conductive or insulating
Conductive or insulating gaskets require more grounding efforts depending on the situation.
Requirements in equipotential bonding and grounding of conductive objects:
Normally: Grounding is necessary, if capacity > 10 pF
Resistance < 1 MΩ at deep measuring voltage [e.g.10 V] In special cases: Grounding is also necessary In speziellen Fällen: ist Erdung zusätzlich erforderlich Independent from capacity: if close to strong charge generating processes if in touch with product flow in the equipment if capacity > 3 pF and in zone 0 or 1 of materials in explosive group IIC
Resistance < 100 MΩ is enough, if:
Charge rate < 1μA and
Capacity < 100 pF
INDUSTRIAL SAFETY AND HEALTH REGULATIONS
The technical regulations on industrial safety and health reflect the regulations on the state of the art, occupational medicine and hygiene and other workplace related findings for the provision and use of equipment and the operation of plants which require monitoring. The Chemistry Committee has created the following professional association regulation “Avoiding Risks of Ignition Resulting from Electrostatic Charges” [BGR 132]. They were adjusted to reflect current law, the developed state of the art and at the same time included in the TRBS 2153 during the development of uniform and coherent rules and procedures. The regulations correspond to the BGI 5127 “Avoiding Risks of Ignition Resulting from Electrostatic Charges” [Information leaflet T 033]. These technical rules apply to the evaluation and avoidance of risks of ignition resulting from electrostatic charges in explosive areas and for the selection and implementation of protective measures to avoid such risks.