With its wide range of sheet gaskets and cut gaskets, TEXPACK® can provide a seal for all types of application from the chemical, petrochemical, food and pharmaceutical sectors to the industrial valve sector. But what exactly does "tightness" mean? One definition of the term "tightness" with regard to a joint, means the absence of evident leaks. The loss of tightness is often a sudden that has to be resolved very quickly. The effects may be dripping or blow-by gas, but may be serious enough to cause a plant shutdown or even fires. This type of loss accounts for a large percentage of the maintenance costs of an industrial facility. According to another definition, "joint-tightness" means "the control of leakages within what are considered to be acceptable limits". The damage caused by this type of leakage, also known as "fugitive emissions" must be assessed in terms of pollution, reduction of plant efficiency and the cost of the fluid lost. The acceptable limit of fugitive emissions must be defined during the plant design phase and for pollutants the limit is set by legal regulations. Regardless of the definition given to the term, today we can state that joint tightness is an objective that must and can be achieved at all times. It is still thought by some in industry that a loss of tightness is a relatively "normal" event, that forms a part of the process and cannot be completely avoided. However, it is now known that a loss of tightness never happens just by chance, but it is always a symptom of a faulty process control. When the process control is defined, the leakages that will occur are also defined.

Tightness factors
Tightness factors are parameters that define the possibility of gasket materials to achieve joint tightness and they are specific for each type of material. Thanks to the tightness factors, it is possible to calculate the stress level to which the gasket will be submitted in order to assure joint tightness, according to the operating conditions and the geometry of the gaskets. Therefore, they represent the main design parameters. The most common tightness factors are:
- ASME code, BS 5500, VSR: tightness factors y, m (based only on mechanical criteria) – DIN E 2505 / σDIN E 28090: tightness factor σVU/L, σBU/L, m/L (based both on mechanical and leakage criteria)
- EN 1591 / EN 13555: tightness factors Qmin(L), Qsmin(L), Qmax (based both on mechanical and leakage criteria) – PVRC: tightness factors Gb, a, Gs (based on Room Temperature Tightness Test))