Couplable flange with clamping jaws for the connection of pipes for the transport of petrochemical fluids, gases and liquefied gases

Abstract

A flange (1) for pipes for the transport of petrochemical fluids, gases and liquefied gases is described, having a bearing surface (11) for clamping jaw (3), which has a peripheral portion (2) bevelled in the direction of support of the jaw (3). Said peripheral bevelled portion (2) is preferably a curved surface.

Description

These and other characteristics of the present invention will become evident from the following detailed description of an embodiment thereof that is illustrated as a non limiting example in the enclosed drawings, in which:

FIG. 1 shows a side view of the flange-jaw coupling according to the present invention in closing position;

FIG. 2 shows a side view in magnified scale of the flange-jaw coupling zone in FIG. 1;

FIG. 3 shows a side view of the flange-jaw coupling with the jaw rotated by 6° in the opening sense;

FIG. 4 shows a side view in magnified scale of the flange-jaw coupling zone in FIG. 3;

FIG. 5 shows a side view of the flange-jaw coupling with the jaw rotated by 10° in the opening sense;

FIG. 6 shows a side view in magnified scale of the flange-jaw coupling zone in FIG. 5;

In the drawings a flange 1 comprises a surface 11 with curved peripheral portion 2 on which a jaw 3 rests which is hinged to a bracket 4 of a coupling for pipes 12 by means of a pin 5 as regards which it is free to rotate.

The movement of the jaw 3 is exerted by a spring 6 controlled to move between a closing position coplanar to the axis of the coupling to an opening position inclined as regards to it by the rotation of a ring or fifth wheel 10 opportunely controlled by hydraulic systems or the like.

The advantages of the present invention are identifiable by analysing the forces which interact in the flange-jaw contact zone 8 (FIGS. 2, 4, 6).

In FIGS. 1 and 2, which show purely exemplified values for “a” and “b”, the equilibrium equation is the following:

R*a=F_a*b

where:

R=force of contact between flange and jaw

F_a=force of friction generated by R (F_a=R×f, where f is the coefficient of friction between metals of the jaw flange coupling)

In order to make the jaw rotate in the opening sense, by applying the load R, it is necessary that: R*a>F_a*b

In the situation of FIGS. 3 and 4 the rotation of the jaw involved an inclination of F_a and R of which it is possible to distinguish the horizontal (F_ao and R_o) and vertical (F_av and R_v) components.

In order for the jaw to open it is now necessary that:

(R_v*a)+(R_o*b)>(F_ao*b)−(F_av*a)

As compared with the situation in FIG. 1-2 the left part of the disequation decreased by virtue of the decrease in the arm to (b remained equal), but such decrease is compensated by the reduction of the friction force F_ao and by the generation of a vertical component F_av favourable to the opening of the jaw 3, therefore the product between F_ao and the b in FIG. 3-4 is smaller than the one between F_a and the b in FIG. 1-2.

If the contact surface of the flange had been flat, the product between F_a and b would have remained constant whereas the one between R and a would have been decreased because of the reduction of a, with the consequent risk of having at a certain point:

R*a<F_a*b

therefore the opening of the jaw could have been blocked.

In the situation of FIGS. 5-6 the jaw has been additionally rotated with the result that as compared with the case in FIG. 3-4 F_av (component in favour of the opening) has increased whereas F_ao (component which opposes to the opening) has decreased.

The disequation

(R_v*a)+(R_o*b)>(F_ao*b)−(F_av*a)

is thus verified for the entire opening rotation of the jaw.

In short the profile of the flange is made as a function of the aforesaid disequation, with the aim to make it result always valid during the opening of the jaw 3.

Claims

1: Flange (1) for pipes for the transport of petrochemical fluids, gases and liquefied gases, characterised in that it has a bearing surface (11) for clamping jaw (3), which has a peripheral portion (2) bevelled in the direction of support of the jaw (3).

2: (canceled)

3: Flange according to claim 1, characterised in that the inequality (Rv*a)+(Ro*b)>(Fao*b)−(Fav*a) is always verified, where: Rv=vertical component of the applied force R;a=arm of the vertical components of the forces;Ro=horizontal component of the applied force R;b=arm of the horizontal components of the forces;Fao=horizontal component of the friction force Fa;Fav=vertical component of the friction force Fa.