Use of ISO 4.6 grade bolt & brittle fracture for

[GD_P]

Hello,

Does anyone have used the ISO 898-1 4.6 grade bolts for pressure bearing parts.
Since for standard flanges under EN 1092-1, PED prohibit use of the 4.6 & 6.8 grade. The reason is both these grades don't have impact/toughness property defined in the ISO 898-1, which is the ESR under PED annex-1. But why this fracture toughness required always, for eg if I have service where the temp will never go below say 30 C, then is there any chance of brittle fracture. What could be the value of temp below which toughness requirements must be followed?

Have you done loose flange calculation as per ASME Sec 8, mand appdx-2 by using ISO graded bolts? If yes, where do you refer for the allow stress values or physical prop (UTS & YTS) at elevated temp?

Thank you in advance.

GD_P

 

[r6155]

Not only fluid temperature or ambient temperature, also failure would result in a sudden discharge of
pressure energy.

See ASME II SA-962 S59. Pressure Equipment Directive—Mechanical Testing
S59.1 Charpy impact testing shall be done at the lowest
scheduled operating temperature, but not higher than 20ºC (68
ºF).
S59.2 The frequency of impact testing shall be the same as
that specified in the product specification for the tension test,
with three individual Charpy test specimens for each required
tension test.
S59.3 The minimum individual energy for the Charpy
impact test shall be 20 ft-lb [27 J].

Regards
r6155

 

[SnTMan]

GD_P, exactly why do you want to use these bolts, rather than a grade permitted by your relevant Code? Hardly seems worth the effort.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[GD_P]

@r6155,

Like ASME Sec VIII Div 1 specifies curves in UCS indicating when impact tests is required but that is for the listed material.
I was looking for such generic curves which can be used for this bolts.

@Mike
"Hardly seems worth the effort."
Agree with you.
As I mentioned they are used for std flanges of En 1092-1, as they are not allowed as per PED I was checking them as per Sec VIII div 1 mand. apdx 2.
But standard flange fails with low strength bolts as well.

GD_P