Heat exchanger tube rupture

API RP 521, Section 3.18.5, indicates that, where the low-pressure side is in the vapor phase, full credit can be taken for the vapor handling capacity of the outlet and inlet lines, provided that the inlet lines do not contain check valves or other equipment that could prevent back flow. The same approach would apply in cases in which the low-pressure side is liquid full, provided that the released material also remains in the liquid state. However, when the low-pressure side contains liquid and vapor is released or generated through a rupture tube, the effective relieving capacity with which the piping system can be credited should be based solely on an equivalent vapor flow. 

The following points need to be considered in quantifying the tube rupture contingency  

The following procedure can be followed in calculating the steady-state contingency of tube rupture. The calculation procedure is different for compressible and noncompressible flow. 

Process engineering and design using Visual Basic 

Noncompressible flow. The normal Darcy equation is used in calculating the flow through a ruptured tube. The pressure drop calculated using the Darcy equation is 

During process design, the greatest opportunity to benefit from dynamic simulation is after adequate design information is available to develop the model, 

If a tube breaks, pressure on the exchanger low-pressure side can spike to a level that exceeds the pressure predicted by a steady-state analysis. This spike is due to pressure buildup before the fluid accelerates out of the shell and/or before the relief device fully opens. 

Dynamic simulation models include fluid inertia and compressibility and exchanger shell expansion to determine the pressure spikes associated with 

The following should be considered with the two-thirds rule  

Stage 1 may last less than one second to several seconds. It is characterized by a very fast transient and a pressure spike immediately after the tube rupture. After the low-pressure side fills with high-pressure fluid, the transition to stage 2 

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Eluor Daniel has the ability to perform a heat exchanger tube rupture transient analysis consistent with the method referred to in RP-521 ("Model to Predict Transient Consequences of a Heat Exchanger Tube Rupture," by Sumaria et ah). This methodology accounts for effects such as the inertia of the low-pressure liquid, the compressibility of the liquid, the expansion of the exchanger shell or tube chaimels, and the relief valve dynamics. Dynamic simulation can be used to meet the following objectives ... 

Sumeria, V.H., J.A. Rovnak, I. Heitner, RJ. Herbert, Model to Predict Transient Consequences of a Heat Exchanger Tube Rupture, Proceedings-Refining Department, Vol. 55, American Petroleum Institute, Washington, D.C., 1976, p.63... 

In production facility design, the most common relieving conditions are (1) blocked discharge, (2) gas blowby, (3) regulator failure, (4) fire. (5) thermal, and (6) heat exchanger tube rupture. Relief valve design How rates are commonly determined as follows. 

Failure of Heat Exchanger Tubes If a heat exchanger shell rating is less than the pressure level of the circulating medium and an internal heat exchanging tube ruptures or leaks it will overpressure the vessel. 

LOCA (Interfacing) e.g. Primary Heat Exchanger Tube Rupture ATWS Anticipated Transients Without Scram Primary Transients,... 

I s C Nominal Nominal Overpressure Flibe to CO2 heat exchanger tube rupture... 

The design of the circuits is very simple. The RRP loops are designed to resist the primary pressure. Isolating valves on the circuit are to avoid the risk of primary water passage outside the containment in the event of heat exchanger tube rupture. A surge tank to compensate for the water expansion from cold shutdown to the full power operating state provides the pressure control of the RRP circuit. 

Pipeline crevasse and equipment leakage accidents Primary circuit pipeline small crevasse Secondary circuit pipeline small crevasse Primary container leakage Main heat exchanger tube rupture Fuel sphere breakage Isolation valve abnormal open Molten salt pipe rupture out of containment... 

Check valve failure Blocked discharge Control valve failure Thermal expansion of liquid Heat exchanger tube rupture Reflux failure and overhead system Loss of reboiler heat Venting of storage tank Failure of individual motor Accidental closure of valve... 

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