Technical specification

Transcription

1 See iorr-

2 Technical specification

3 SNO. DESCRIPTION UNIT I QTY 1 Hydraulic Snubber with Total stroke 140mm, working stroke 80mm, length NOS 10 at half stroke 49Rmm, dia 84mm and maximum load level] 7.5 KN 2 Hydraulic Snubber with Total stroke 185mm, working stroke 120mm, length NOS 6 at half Stroke 643nun, dia 84mm and maximum load level 17.5 K 1 3 Hydraulic Snubber with Total stroke 140mm, working stroke 80mm, length NOS 6 at half strcu«: 19 'mm, dia -lrnm and maximum load level 35 K.. - SS C 1: pt: 01 clamps of size x ] 20 rnm with co' necting pin ~OS SS C Type vo k clamps of size 76 7 x 1')0 mm with connecting pin NOS 10 J - I I I 6 I SS U I'ypc yolk clamps of size 88.9 x 215 mm with co:mecting pin I NOS I 7 SS U Type yolk clamps of size 114.3nun x 205 mm with connecting pin NOS 10 I 8 SS.U Type yolk clamps of size 168.3mm x 90 nun with connecting pin NOS 10 -

4 TE NbE «-. ~PE'I. NO; PFB 3COOO /sp 11'092> /1<,14. ~~-», Tender specification for Procurement of Snubbers 1.0 INTRODUCTION This, note discusses the general specifications for the hydraulic/mechanical snubbers used for PFBR. Snubbers are used in the high temperature pipelines to limit the seismic induced forces in the pipe lines below the acceptable limits \Nhile allowing for the free thermal expansion during normal operating conditions. Various parameters to be specified for the snubbers used for this purpose vary from pipe line to pipe line based on its size, orientation, operating condition and induced seismic forces and moments, The note gives detailed specifications for the snubbers required for various pipelines in PFBR. 2.0 DEFINITIONS Detailed definition of various terms used in the snubber specifications for the pipe lines are explained below Activation: The ch :... ~,.....rl:~:......:-....;,......~...,...~... h resists the rapid displacement of the II "~ll~'" u, VVllunlVI. III. UI' U.\:'" '='IIUt..l~CI ii~i-=-l attached pipe Of component.. Break away: The force required to initiate the movement in one direction. Dead band: The free axial movement of the restraint between the two activation levels in opposite directions. Drag: The load required to maintain the snubber movement at specific velocity Rated load: The design load capacity for the restraint based on the use of level-a service limits defined by ASME Boiler and Pressure vessel code. Release rate: The rate of the restraint axial movement, after the activation of the restraint under specified load. PFBRJ30000/SPII 0931RA Page 10f25

5 ..., Spring Rate: The linear approximation of the relationship of the load displacement characteristics of the restraint. Stroke: The maximum available axial movement of the device. 3.0 FUNCTIONAL PARAMETERS FOR SNUBBERS The functional parameters to be specified for the hydraulic/mechanical snubbers are the following» Activation level» Release rate» Break away» Drag» Dead band» Load rating» Spring rate 1> stroke Th,... lie Q activation ll VClUV I 1,...",...1"'ar. leve... I bec s...ecltie fj.. lileu.. :- III J. lei III;:) VI -~ acceleration l 1 VI -- velocity IVI,; based on the type of snubbers used (hydraulic or mechanical). The activation of the snubber is triggered when the design characteristic (velocity or acceleration) reaches the pre determined value in either direction. The activation level is determined by rapid application of a single direction load of increasing velocity or acceleration. Generally the activation level for hydraulic snubbers is given in terms of velocity and that of mechanical snubbers are given in terms of acceleration. Only a small fraction of the rated load is normally required to activate a snubber. Release rate is the velocity at which restraint motion occurs after activation has taken place. The release rate magnitude depends on the loading magnitude and is an indication of the recovery rate of the restraint as it returns to the inactivated condition. Break away and drag can be determined using a load cell to measure the force required to initiate the movement and the force required to move the snubber at specific velocity respectively. PFBRl3 OOOO/SPII 093 IRA. Page 2 of25

6 -.. -~-- Dead band can be determined by measuring the distances traveled by the restraint before it activates in opposite directions. The dead band can have significant effect on performance at all loading levels. Load rating may be determined by test or analysis in accordance with ASME BPVC Section III, Subsection NF. Spring rate shall be determined dynamically. Additionally a static spring rate may be determined if required. The applied loads in tension and compression divided by the recorded displacements in tension and compression including dead band describe the spring rate. The amount of stroke is typically dictated by the amount of thermal expansion experienced at the location where the restrained to be used. 4.0 FUNCTIONAL SPECIFICATION FOR HYDRAULIC AND MECHANICAL SNUBBRES 4.1 Design requirements Design requirements of the snubbers such as stroke length and seismic loads are specific to each pipe line and are listed in annexure-1. The general design requirements are listed below. The Frequency range will be in from O.5Hz to 50Hz Angular offset should be minimum It must have a travel indicator to verify the good operating position. Support for snubbers including end brackets must be designed with consideration of side loads from unexpected events such as fast transient under sudden closure of valve. Snubber must allow thermal movement within a short time (1-2 minutes) after cessation of vibratory motion. Snubber stiffness should be identical in both tension and compression 4.2 Operational Requirements The snubbers should allow free and smooth thermal expansion during normal operating condition and should able to lock when the velocity or acceleration PFBRJ30000/SP/I0931RA Page 3 of25

7 exceeds the specified limit. The working fluids and seals must me able withstand the high temperature during accidental conditions. 4.3 Functional parameters for hydraulic snubbers Typical values of the functional parameters for the hydraulic snubbers described in para-3 piping are given below [1,2] Activation level or locking speed - 2 mm/s Lost motion (dead band) - 1 mm Break away - 5 % of maximum load Release rate - 2 mm/s Operating Temperature - 20 to e Frictional resistance FN where load under normal operating condition including OBE. Frequency Stroke Lead rating range Hz to 33 Hz - Furnished from thermal analysis result (as per the values given in attached tables for various systems in annexure-1). From seismic analysis for OBE and SSE (as per the values given in annexure) 4.4 Functional Parameters for Mechanical Snubbers Typical values of the functional parameters to be specified for the hydraulic snubbers which are described in para-3 is given below. Activation level or locking speed g Lost motion (dead band) - 1 mm Break away - 2 % of maximum load Release rate - 2 mm/s Operating Temp - 20 to 100Ge Frictional resistance FN where load under normal operating condition including OBE. Frequency Stroke range Hz to 33 Hz - Furnished from thermal analysis result PFBRJ30000lSPIl 0931RA 'Page 40f25

8 Load rating 4.5 Specific material requirements - From seismic analysis for OBE &SSE (as per the values given in annexure) In the case of hydraulic snubbers the material used for the body and elastomeric seals should be able withstand an operating temperature of around eo-c and humidity level of 100% for 40 years in the radiation environment of 60 Mega rad. In case of mechanical snubbers the lubricants used should be able to withstand high operating temperature of e and humidity level of 100% for 40 years. The raw materials used should be in accordance with ASME or RCC-MR specification. The performance be provided by the supplier. 5.0 APPLICABLE CODES test certificates for all the above mentioned requirements should Applicable codes and standards for the design and manufacturing and testing of the snubbers are ASME section III NF and ASME QME , section-qor or any equivalent code. 6.0 QUAI.IFICATION PROGRAMME The qualification programme for snubbers must demonstrate all the functional and environmental parameters specified for the snubbers and in accordance with the applicable codes given in aforementioned paragraph. Snubbers can be qualified by testing and analysis or it may be qualified by an extension of a qualification programme that has been previously performed on similar assembly. The environmental parameters must include the operating temperature, humidity, radiation etc and the functional parameters must include all the parameters mentioned in Para and All parameters shall be determined at recorded room temperature and at a temperature of 100 C or at the specified maximum design temperature which ever is higher. Temperature correction factors for higher or lower temperatures shall be recorded at the beginning and end of each of the. tests. Tests shall be performed with the restraint at the mid stroke position unless and otherwise required. One snubber in each. capacity shall be tested for the maximum stroke requirement. A brief description of the Functional test procedure is given below. PFBRl3 OOOO/SP/l0931RA Page 5 of25

9 ----~-=---=== ~ ~, The activation level shall be tested in each direction. The acceleration and velocity can be recorded as a function of time and activation level can be determined from this data The release rate shall be tested and recorded in each direction at 5%, 10%, 50% and 100% of rated load and at emergency load. Break away shall be determined at the initiation of the drag test in each direction or during the test performed specifically to determine beak away drag. The force corresponding with the initiation of movement shall be recorded. Drag shall be recorded in each direction. The values of drag and velocity shall be recorded. Drag shall be performed throughout the entire range of travel to demonstrate the drag characteristics. Dead band can be recorded during the activation level testing described above or during a separate test performed specifically for determination of dead band. Spring rate shall be tested by a dynamic cyclic loading equal to the rated load (or specified load). The peak displacement range including the dead band shall be obtained during the dynamic cyclic test through the peak force range. The peak force range shall include load applied in opposite directions. Restraint movement shall be centered about 1/4, 112and 3/4 stroke locations. Testing frequency shall be from 1 to 33 Hz at intervals approximately 3 Hz. Each frequency shall last not less than 10 sec. responses at each frequency shall be recorded as load displacement curves. No extreme change in displacement should be observed from one frequency to next. As this could indicate that the fundamental frequency is within 1 to 33 Hz. The stroke is a parameter to be dimensionally verified but no further testing is performed. The measured stroke of the snubbers must be equivalent to the indicated travel on the 'name plate. The snubber must be free moving over the full working travel. Hydraulic fluid loss during the testing shall be recorded. PFBRJ3 OOOO/SPII 0931RA Page 6 of25

10 8.0 DOCUMENTATION Documentation must contain the technical details and design drawings. Technical detail must include the detailed specification, type of fluid used in shock arrestors, functional parameters and test certificates for the functional qualification programme for various functional parameters. Design drawing must show all the dimensions long with the end brackets and fittings. 9.0 INSTALLATION REQUIREMENTS The scope of the supplier incfudes installation in actual site and demonstration of various aforementioned functional parameters. Towards this the supplier must provide a detai/ed installation procedure clearly mentioning the scope, responsibility, pre installation check and installation, welding details and post installation checking procedure. 10 MAINTENANCE AND INSPECTION REQUIREMENTS The system should be maintenance free. Apart from initial inspection, there shall be provision for in-service inspection of essential requirements such as functionality. The in service inspection requirements and schedule for the given type of snubbers should be properly mentioned in the inspection manual. There should be provisions for online condition monitoring of the snubbers. 11 CONCLUSION This note describes the major specifications of the snubbers including functional parameters. qualification procedure, installation and maintenance of snubbers for the pipe lines for PFBR. This will form the basis for the procurement, installation and maintenance of the snubbers. REFERENCES 1. ASME QME "Qualification of active mechanical equipment used in Nuclear Power Plants" 2. ETEC-TDR-82-2 "Snubber qualification test requirements" PFBRJ30000/SP/I093/RA Page 70f25

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