diferreira
Mechanical
- Jul 17, 2014
- 2
Hi all,
I am having a discussion here and would appreciate if someone could help.
I understand that for API600 valves there is an obligation to use Heavy Hex Bolting per paragraph 5.10.1.
On the other hand, API602 on paragraphs 5.5.5 and 5.5.6 doesn´t specify the same, it just mentions that the threads must be of Classes 2A or 2B with ASME B1.1 threads.
So I went to look further on ASTM A194 section 9, it says that "9.1 Nuts shall be hexagonal in shape, and in accordance with the dimensions for the hex or heavy hex series, as required, by ASME B 18.2.2 and ASME B 18.2.4.6M. Unless otherwise specified, the American National Standard Heavy Hex Series shall be used and nuts shall be either double chamfered or have a machined or forged washer face, at the option of the manufacturer, and, conform to the angularity requirements of ASME B 18.2.2 and ASME B 18.2.4.6M."
Comparing the mechanical property requirements from ASTM A194 2H and ASTM A193 B7 as an example, I see that the B7 Yield Strength is 105ksi and Tensile Strength is 125ksi. For the 2H, the proof load for Hex Series is 150ksi and for Heavy Hex Series is 175ksi. So, technicaly, if the Nut has enough bearing area it should be safe to use the Hex Series.
The other point is that ASME VIII - Div 1 on UCS-11 says that I may use nuts of other dimensions than the Heavy Series if the flanged connection is in accordance with the rules in Mandatory Appendix 2, which says that the bolted joint is compliant with it, when the gaskets are entirely within the circle enclosed by the bolt holes and with no contacts outside this circle and if the mechanical properties of the nuts are compatible with the studs.
With this in mind, why shouldn´t I specify for my product the Hex Series for the body-bonnet and packing joints for API602 valves?
I am looking for technical answers, not the ones like: "It´s such a small difference in price, so why to bother?".
Thanks!
Diogo
I am having a discussion here and would appreciate if someone could help.
I understand that for API600 valves there is an obligation to use Heavy Hex Bolting per paragraph 5.10.1.
On the other hand, API602 on paragraphs 5.5.5 and 5.5.6 doesn´t specify the same, it just mentions that the threads must be of Classes 2A or 2B with ASME B1.1 threads.
So I went to look further on ASTM A194 section 9, it says that "9.1 Nuts shall be hexagonal in shape, and in accordance with the dimensions for the hex or heavy hex series, as required, by ASME B 18.2.2 and ASME B 18.2.4.6M. Unless otherwise specified, the American National Standard Heavy Hex Series shall be used and nuts shall be either double chamfered or have a machined or forged washer face, at the option of the manufacturer, and, conform to the angularity requirements of ASME B 18.2.2 and ASME B 18.2.4.6M."
Comparing the mechanical property requirements from ASTM A194 2H and ASTM A193 B7 as an example, I see that the B7 Yield Strength is 105ksi and Tensile Strength is 125ksi. For the 2H, the proof load for Hex Series is 150ksi and for Heavy Hex Series is 175ksi. So, technicaly, if the Nut has enough bearing area it should be safe to use the Hex Series.
The other point is that ASME VIII - Div 1 on UCS-11 says that I may use nuts of other dimensions than the Heavy Series if the flanged connection is in accordance with the rules in Mandatory Appendix 2, which says that the bolted joint is compliant with it, when the gaskets are entirely within the circle enclosed by the bolt holes and with no contacts outside this circle and if the mechanical properties of the nuts are compatible with the studs.
With this in mind, why shouldn´t I specify for my product the Hex Series for the body-bonnet and packing joints for API602 valves?
I am looking for technical answers, not the ones like: "It´s such a small difference in price, so why to bother?".
Thanks!
Diogo
