I'm sorry this post is a very long one.
It should be clear it is just my interpretation.
1. On the subject Pressure Equipment, material 316L, the Basic rule of PED is given in PED Annex I
7. SPECIFIC QUANTITATIVE REQUIREMENTS FOR CERTAIN PRESSURE EQUIPMENT
The following provisions apply as a general rule. However, where they are not applied, including in cases where materials are not specifically referred to and no harmonized standards are applied, the manufacturer must demonstrate that appropriate measures have been taken to achieve an equivalent overall level of safety.
……..
7.5. Material characteristics
Unless other values are required in accordance with other criteria that must be taken into account, a steel is considered as sufficiently ductile to satisfy 4.1 (a) if, in a tensile test carried out by a standard procedure, its elongation after rupture is no less than 14 % and its bending rupture energy measured on an ISO V test-piece is no less than 27 J, at a temperature not greater than 20 ºC but not higher than the lowest scheduled operating temperature.
As you can see, you can understand the material must be impact tested.
2. For your case, you have to demonstrate that for your equipment made in 316L, “appropriate measures have been taken to achieve an equivalent overall level of safety”.
It appears that you have to perform an impact testing as proving your material has enough “bending rupture energy measured on an ISO V test-piece”. However, if you are able to demonstrate in front of Notified Body that your material, being an austenitic SS, is not subject to a ductile/brittle transition at the foreseeable conditions the equipment will be exposed to, it's not mandatory to perform a impact test.
3. More guidance can be found in 13445-2 (annex B), which is not PED but is a PED harmonized standard.
For pressure equipment with design temperature equal to or less than 50 °C this annex specifies three alternative methods for establishing criteria for the prevention of low temperature brittle fracture1) of steels in the form of plate, strip, tubes, fittings, forgings, castings, flanges, fasteners and weldments used in pressure parts. The criteria are based on impact energy requirements at specified temperatures for the base material, heat affected zone (including the fusion line) and weld metals.
First method of 13445-2 is a “Code of Practice” in line with PED requirements:
Method 1 Code of Practice:
a) technical requirements based on the choice of TR = T_27J as specified in harmonized European Material Standards and on the assumption that it is possible to achieve these minimum properties after fabrication. Calculated from the principles of fracture mechanics used for method 2 for C and CMn steels with yield strength < 460 MPa
and
b) based on operating experience for Ni-alloyed steels with Ni ≥ 3 % up to 9 %, for austenitic steels and for bolts and nuts.
It appears that for austenitic steel there is a criterion for the prevention of low temperature brittle fracture based on operating experience. Which one?
4. Considering now B.2.2.5 “Lowest minimum metal temperatures for austenitic stainless steels” chapter:
Solution annealed austenitic stainless steels according to Table B.2-11 can be applied down to temperature TM without impact testing, except when impact testing is required by the material standard. E.g. EN 10028-7 requires impact testing at room temperature above 20 mm thickness for use at cryogenic temperatures (below -75 °C according to EN 10028-7:2007).
……………..
Where the design temperature is below -105 °C weld metal and heat affected zones for austenitic stainless steels shall meet additional requirements of EN 13445-4:2009, clause 8.
and
5. The minimum metal temperature TM is the lowest temperature determined for any of the following conditions:
⎯ normal operations;
⎯ start up and shut down procedures;
⎯ possible process upsets, such as flashings of fluid, which have an atmospheric boiling point below 0 °C;
⎯ during pressure or leak testing.
So now it seems that you can use an austenitic steel without impact testing when temperature TM is higher than minus 75 °C . For TM within cryogenic temperatures you have to see the requirements of EN 10028-7. And for design temperature below -105 °C, special considerations must be applied.
Yes, it seems to be reasonable!
True or not true for your case? Strictly speaking, 316L isn’t in Table B.2-11 while 1.4404 EN10028-7 is in this table.
For sure it's true for 1.4404.
6. Now, if you are looking to the point 4.1.6, you can find a general requirement for materials to be used for pressure-bearing parts:
Steels shall have a specified minimum impact energy measured on a Charpy-V-notch impact test specimen (EN 10045-1:1990) as follows:
⎯ ≥ 27 J for ferritic and 1,5 % to 5 % Ni alloy steels;
⎯ ≥ 40 J for steels of material group 8, 9.3 and 10
at a test temperature in accordance with Annex B, but not higher than 20 °C.
The other requirements of Annex B shall also apply.
Well, you may note that material group 8 is Austenitic steels, i.e. 8.1 Austenitic stainless steels with Cr ≤19 %, 8.2 Austenitic stainless steels with Cr >19 %, etc, so now you can understand your 316L (as Austenitic SS) must be tested at impact energy of 40J (not 27J) measured at test temperature (which one?), unless you are able to demonstrate to NB that B.2.2.5 is "other requirement of Annex B" and it's valid also for 316L.
And remember 13445 Annex B is not PED, it's just a PED harmonized requirement.
7. And what does it means” where the design temperature is below -105 °C weld metal and heat affected zones for austenitic stainless steels shall meet additional requirements of EN 13445-4:2009, clause 8”?
Looking now in EN 13445-4:2009.
For austenitic steels:
When the minimum design temperature TM of the vessel is less than -105 °C the weld and heat-affected zones shall meet a minimum of 40 J when tested at -196 °C.
NOTE 2 For practical reasons, the test temperature of -196 °C is standardised for all austenitic steel testing of any design temperature below -105 °C.
For filler metals of type 19 9 L, 19 9 Nb, 19 12 3 L, 19 12 3 L Si, 19 13 4 N L, 25 20 L, 25 22 2 N L, 27 31 4 Cu L and nickel based filler metals this may be demonstrated on procedure qualification tests, and further production test plates are not required.
For other weld metal composition and where the weld metal ferrite content exceeds 12 FN, each batch of weld metal shall demonstrate the required impact properties, or a production test plate for impact properties shall be carried out per vessel at -196 °C.
As a possible logical approach to exit this mélange, you may proceed as bellow.
For your equipment made in 316L consider the requirements to have an impact energy of 40J, obtained on Charpy-V-notch impact test specimen , test temperature being TM when TM higher than -105 C, and -196 C when TM is less than -105 C. This would be considered as "in-line" with the PED requirement to ask for impact test "at a temperature [...] not higher than the lowest scheduled operating temperature."
Correct the impact energy value (40J) if you are using Sub-sized specimens as per B.3.2, EN 13445-2. Apply all applicable rules and be prepared for a long discussion on this subject with NB.
Evaluate carefully the entire rules set for fabrications (particularly for welds) given in 13445- Part 4: Fabrication and apply them even are not mandatory for your case; this approach would protect you for interminable discussions.
Ask for God mercy when discuss with Notified Body!
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