How to calculate duration gap

API 610 Major Changes from 5th through 10th EditionsItem5th Ed6th Ed7th Ed8th Ed9th/10thEdition *Pump TypesNo limitation on pump typesClose coupled, two stage overhung or double suction overhung pumps require purchaser approval• Close coupled,two stage overhung or double suction overhung and ring section single casing pumps require purchaser approval.• In-line pump specified is rigid coupled type.• Rigid coupled in-lines, horizontal foot mounted overhung, and built in mechanical seal pumps added to list requiring customer approval.• In-line pump must be bearing frame type unless specified by the purchaser.Foot mounted design now allowed, if approved by customer, if servicetemp. is <150 deg. C (300 deg. F).Casing design pressureDesign for max. discharge pressure for serviceDesign for max. discharge pressure plus allowances for head and speed increaseDesign for max. discharge pressure plus allowances for head and speed increaseDesign pressure no less than 600 psigNo change.FlangesPressure class not specifiedPressure class not specifiedPressure class not specified300 RF minimum implied (based on 600 psig casing design pressure)No change.Casing jointsExternally confined gasketsMetal to metal joint with confined controlled compression gasketMetal to metal joint with confined controlled compression gasketMetal to metal joint with confined controlled compression gasketNo change.BoltingType of bolting not specifiedStuds and nuts preferred to cap screwsStud and nuts preferred to cap screwsStuds and nuts required. Cap screws require purchase approvalNo change.Casing mountCenterline mount for T>350oFCenterline mount for T>350oFCenterline mount for T>350oF• Casing mount (with baseplate) must be sufficiently rigid to limit coupling end shaft displacement to levels permitted by API 610. A bearing housing support (frame foot) cannot be used.Centerline mounting required for horizontal overhung pumps.• Casing mount (with baseplate) must be sufficiently rigid to limit coupling end shaft displacement to levels permitted by API 610. A bearing housing support (frame foot) cannot be used.Still requires centerline mounting for horizontal overhung pumps except, when approved by customer, foot mounted horizontal overhung may be usedif service temperature is < 150 deg. C (300 deg. F).Auxiliary connections to casingSchedule 80Schedule 80Minimum Schedule 160Minimum Schedule 160No change.Casing ventVent required unless pump design is self ventingVents required unless pump design is self ventingNeed for venting based on capability to prevent loss of prime during starting sequenceNeed for venting based on capability to prevent loss of prime during starting sequenceNo change.Shaft ConcentricityMachined and assembled for concentric rotation (TIR limits not specifiedConcentricity limit specified at 0.001 inch TIRConcentricity limit specified at0.001 inch TIRConcentricity limit specified at 0.001 inch TIRNo change.

2Item5th Ed6th Ed7th Ed8th Ed9th/10thEdition *Shaft DeflectionShaft sized to limit deflection to max. of 0.002 inch at face of stuffing boxShaft sized to limit deflection to max. of 0.002 inch at face of stuffing boxShaft sized to limit deflection to max. of 0.002 inch at face of stuffing boxShaft sized to limit deflection to max. of 0.002 inch at the faces of the primary mechanical seal.No change.Seal chambersNo minimum dimensionsspecified. Stuffing box face must be machined to accept mechanical seal gland.No minimum dimensions specified. Stuffing box face must be machined to accept mechanical seal gland.Minimum seal chamber dimensions for mechanical seals specified. Results in a seal only design.Standardized seal chamber dimensions specified (per API 682).No change.Mechanical sealsMechanical seal is purchaser optionMechanical seals unless otherwise specifiedMechanical seal unless otherwise specified. Fixed throttle bushing required on single and double sealsCartridge mechanical seals required. Default seals are to API 682. If non-682 seals are permitted, cartridge seals must meet requirements specified in API 610:• 682 seal chamber dimensions• 682 connection symbols• dry running secondary allowedAll seal arrangements to be per API-682/ISO21049. Seals now specified by “Category”. See API-682, Para. 1.2.In summary: -Category 1 = non-API.-Category 2 = same as API-610, 8thEdition.-Category 3 = full API-682.Operating point on curveNo requirements specifiedBEP between rated and normal pointBEP between rated and normal pointPreferred Operating Region70 to 120% of BEP. Must meet the new vibration criteria in this region. Rated capacity in 80-110% of BEP. BEP preferred to be between rated and normal points.Allowable Operating RegionFlow range within a 30% increase allowable vibration levelsNo change.Component BalanceNo balance level specified. Dynamic balance dependent on operating conditionsDynamic balance required. No balance levels specifiedDynamic balanced to 4 W/NDynamic balanced to 4 W/NDynamic balancing changed to ISO 1940-1 Gr. 2.5 (equiv. to 8W/N. Tighter balancing to ISO 1940-1 Gr. 1.0 (equiv. to 4W/N) only required when specified. (See Note 1 at end of this review).VibrationUnfiltered Vibration limited to 0.002 inch P-P for ball bearings and 0.0025 inch P-P forsleeve bearings. Filtered levels not addressedVibration velocity <0.3 in/sec unfiltered and <0.2 in/sec filteredVibration velocity <0.3 in/sec unfiltered and <0.2 in/sec filtered<0.12 in/sec overall and <0.08 in/sec. at discrete frequencies inside preferred operating region. Increase of 30% permitted in allowable operating region< 0.20 in/sec and 0.67 Vu (unfiltered velocity) at discrete frequencies. Increase of 30% permitted in allowable operating range.(For hydrodynamic brg vib. limits, see API Table 8).