Nozzles, inspection

RNL NDT STUDIES RELATED TO PWR PRESSURE VESSEL INLET NOZZLE INSPECTION... 

In this paper, a review Is given of the Work performed at RNL In the development of a laboratory-based Inspection system for Inlet nozzle Inspection. The main features of the system In Its current stage of development are explained. 

Further details of the ultrasonic techniques and procedures used In recent nozzle Inspections are given In section 5. 

A second method of correcting for beam deviation Imposed by the vessel geometry Is to use a self-skewing probe holder which automatically rotates the probe about an axis normal to the Inspection surface by an amount which returns the beam to the r-z plane. Such a probe holder has been developed within the UKAEA, Initially for tlme-of-fllght diffraction lnspectlons(5), and now pulse-echo lnspectlons(6) of the nozzle-to-vessel weld. The essential feature of the holder Is a mechanical link between the tilt angle of the probe holder on the surface and the probe holder skew angle needed to bring the beam back Into the required plane (Fig 5). Both types of probe holder have been Incorporated lir the RNL Inspection system for nozzle Inspection from the vessel shell course. 

Figure 6 AIR-1 articulated robot arm with six degrees of freedom Robot performs ultrasonic inspection of a large nozzle weld on a BWR main circulation pipe.

The 3D-inspection system can be applied to many complex inspection tasks where ordinary XY scanners can not perform the job, e.g. nozzle welding inspections and nozzle inner radius inspection in nuclear and petrochemical environments. 

The system has recently been used with success for inspection of 11 inclined nozzle welds during the R1 SPRINT project at Vattenfall Ringhals, Sweden during the summer 1997. At the moment a full system and personal qualification is prepared for inspection of the pressurizer spray nozzle weld at Vattenfall Ringhals, block 2 at May, 1998. 

Figure 2 AIR-1 robot mounted on incbned inspection nozzle...

LORUS is also used for inspection of piping that has been on supports or sleepers for some time, to see whether corrosion has developed at the contact points. But the technique can also be used for corrosion detection under insulation, inspection of pipelines at dike and road crossings, nozzle reinforcement pads or craek detection in suspension systems for railway cars. 

Other examples of government and military applications of laser-based profilometry include the evaluation of rocket thruster nozzles to locate and measure flame erosion remote inspection of hypervelocity test track and the measurement of sludge deposits on tube internal surfaces. 

The AeroSizer, manufactured by Amherst Process Instmments Inc. (Hadley, Massachusetts), is equipped with a special device called the AeroDisperser for ensuring efficient dispersal of the powders to be inspected. The disperser and the measurement instmment are shown schematically in Figure 13. The aerosol particles to be characterized are sucked into the inspection zone which operates at a partial vacuum. As the air leaves the nozzle at near sonic velocities, the particles in the stream are accelerated across an inspection zone where they cross two laser beams. The time of flight between the two laser beams is used to deduce the size of the particles. The instmment is caUbrated with latex particles of known size. A stream of clean air confines the aerosol stream to the measurement zone. This technique is known as hydrodynamic focusing. A computer correlation estabUshes which peak in the second laser inspection matches the initiation of action from the first laser beam. The equipment can measure particles at a rate of 10,000/s. The output from the AeroSizer can either be displayed as a number count or a volume percentage count. 

Retrieval by vibration levels. Inspection of data provided by this mode can be useful in determining compressor fouling, compressor or turbine blade failure, nozzle bowing, uneven combustion, and bearing problems. 

I xtemal inspection criteria are provided by these standards for foundation and supports, anchor bolts, concrete or steel supports, guy wires, nozzles, sprinklers pipe hangers, . rouiuling coiiiiee(ions, protective coatings, insulation, and external metal surfaces. 

It must be pointed out that a Code stamp does not necessarily mean that the vessel is fabricated in accordance with critical nozzle dimensions or internal devices as required by the process. The Code inspector is only interested in those aspects that relate to the pressure-handling integrity of the vessel. The owner must do his own inspection to assure that nozzle locations are within tolerance, vessel internals are installed as designed, coatings are applied properly, etc. 

Some flame arrester designs allow in-place inspection (via a removable honsing cover plate) however, others have to be removed from the vent nozzle or in-line piping to inspect the flame arrester element. 

Figure 11.6 Examples of methanol synthesis converters (a) tube-cooled, low-pressure reactor A nozzles for charging and inspecting catalyst B outer wall of reactor as a pressure vessel C thin-walled cooling tubes D port for catalyst discharge by gravity (b) quench-cooled, low-pressure reactor, A,B,D, as in (a) C ICI lozenge quench distributors (Twigg, 1996, pp. 450, 449 reproduced with permission from Catalyst Handbook, ed. M.V. Twigg, Manson Publishing Company, London, 1996.)...

Suction and discharge nozzle welds shall be inspected in accordance with 2.11.3.4.2. The purchaser will specify when the following additional inspection methods are required ... 

Thus, the discharge nozzle loads are too large. By inspection, if MKDp is reduced by 50 percent to 1356 Nm, the resulting principal stress will still exceed 41 MPa. Therefore, the maximum value for MXDp will be twice MXDj2, or 1900 Nm. 

For a 3 X 4 X 7 vertical in-line pump, the proposed applied nozzle loadings are as given in Table F-3B. By inspection, FZ5a, AZZ5a, and MXDp are greater than two times the values shown in Table 2. IB. As stated in F.2, these component loads are acceptable provided that the calculated principal stress is less than 5950 psi. The problem is to determine the principal stress for the suction nozzle and the discharge nozzle. 

Thorough visual inspection of the system including piping and piping supports, nozzle locations, placement of signs, and openings that would... 

There are several methods of layering in common use ( ) thick layers shrunk together (2) thin layers, each wrapped over the other and the longitudinal seam welded by using the prior layer as backup and (3) thin layers spirally wrapped. The code rules are written for either thick or thin layers. Rules and details are provided for all the usual welded joints and nozzle reinforcement. Supports for layered vessels require special consideration, in that only the outer layer could con-triDute to the support. For lethal service only the inner shell and inner heads need comply with the requirements in Subsec. B. Inasmuch as radiography would not be practical for inspection of many of the welds, extensive use is made of magnetic-particle and ultrasonic inspection. When radiography is required, the code warns the inspector... 

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