B0-e

Open current module guide

A proof of nozzle loads is not necessary if the following conditions are satisfied as well:

·         The nozzle pipe must be fully connected to the basic shell.

·         The minimum wall thickness of the nozzle pipe must be according to DIN 28115 with ferritic materials, and according to DIN 28 025 part 1 or part 2 with austenitic materials.

·         Support lengths and flexibility of the connected pipe must satisfy support length table or flexibility nomogram of AD 2000-Merkblaetter section HP 100 R (LV Module HPR).

·         The diameter of the nozzle di must not be greater than 0.3*Di.
The design for internal pressure per AD 2000-Merkblaetter B 3, B 9 and B 1 must be done with a 10 percent increased internal pressure, with a reinforcement of the basic shell and/or the nozzle, if necessary.

·         Design is not done for failure due to creep fatigue.

·         The number of start-ups and removals does not exceed the allowable numbers per 2000-Merkblatt S1 section 4.2.

Requirements of the Pressure Equipment Directive

Requirements of the PED

In Annex I, Section 3.2, the PED requires that a strength test in the form of a hydrostatic pressure test be carried out as part of the final inspection. This pressure test is intended to check the aspect of the required compressive strength.

The test pressure must be at least equal to the value specified in section 7.4 of Annex I:

(1) PT = PS * 1,43 or

(2) PT = PS * 1,25 * K20 / KTS

The higher of the two calculated test pressures PT is decisive.

The test pressure factor FP = 1.25 * K20 / KTS in formula (2) above takes into account the temperature-dependent strength values.

The test pressure factor FP = 1.43 in formula (1) means that in the test state a stress level of 95% of the yield strength corresponding to a residual safety factor of 1.05 is achieved.

The aforementioned regulations apply to pressure vessels, pressure-retaining equipment, pipelines and assemblies.

Replacement tests for the hydrostatic pressure test

The PED expressly permits substitute tests if the hydrostatic test is disadvantageous or not feasible:

(a) a gas pressure test

(b) other test pressures

(c) verification on a statistical basis

2.1. Gas pressure test

The gas pressure test should only be used in exceptional cases, e.g. if the hydrostatic pressure test is disadvantageous or not possible. If a lower test pressure is used for safety reasons, additional measures must be taken, e.g. non-destructive testing, to achieve an equivalent level of safety.EN13445:

The pressure test is part of the acceptance test.

The hydrostatic test (hydraulic pressure test) is performed as a pressure test as standard.

If this is not appropriate, this test can be replaced as follows:

(a) Pneumatic test (gas pressure test). The gas pressure test is much more dangerous than the hydrostatic test. Therefore, this test may only be carried out under the following conditions:

-       Filling the pressure vessels with liquid is inappropriate due to the design and construction;

-       the pressure vessels are to be used in processes in which even small traces of liquid cannot be tolerated;

-       after timely consultation during the design phase;

2.2 Other test pressures

The level of the test pressure must be chosen so that the hydrostatic pressure test, with due regard to safety factors, ensures that no damage to the pressure equipment occurs.

3. Requirements of the regulations

For the performance of the hydrostatic pressure test, additional aspects have to be considered which are not explicitly stated in the PED but which can be derived from the specifications. The following table considers the essential aspects in the individual regulations: