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Bolting (studs and nuts)

The studs and nuts are based on TU 3647-005-51705251-11 “Specification for high pressure pipe connections”. The specification is based  on the recommendations of the Russian State Standards GOST 12.2.003, GOST 2.114 and FNP Federal Rules and Regulations “Oil and gas industry safety regulations”, TR CU 010/2011 “on the safety of machinery and equipment”, TR CU 032/2013 “On safety of equipment operating under excessive pressure”, GOST 28919, GOST 33259, GOST R 53561, GOST 1759.0, GOST 20700, ASTM A320/A320M, ASMA193/193M, ASTM A194/194m, API 6A, NACE Mr 0175.

Connection elements can be supplied in bulk or as a full set.

When ordering, please specify the following:

  • dimension and thread series;
  • full stud length
  • length of screwed end for stud bolts;
  • material of stud and/or nut and strength group (0.2 yield strength and hardness limits) or material category with reference standard.

All products shall be enclosed with suitable manufacturer’s certificates. Individual deviations from design and reference documents not affecting the product specification or the contract requirements as well as the product appearance can be acceptable based on manufacturer’s approvals.

Main parameters and characteristics of flanges

Parameter Value
Stud Nut
Thread profile
– metric
– inch
as per GOST 9150
as per ASME/ANSIB1.1
Dimension (nominal OD of thread)
– metric
– inch

from М14 to М76
from 3/4” to 3”

Thread series
– metric
– inch
6g

Metric 27mm OD threads are coarse pitch. OD > 27 mm are 3mm pitch unless otherwise specified by the Customer.

As agreed with the customer we can supply:

  • studs and nuts with left-hand thread;
  • studs with extended or reduced length of the threaded part

Operating medium in pipeline with flanges: oil, gas, gas condensate, water, drilling mud, their mixtures and flushing water with volume fraction of:

  • CO2 upto 6% (K1 as per GOST 13846);
  • CO2 and H2S upto 6% each (K2 as per GOST 13846);
  • CO2 upto 17% and H2S upto 27% (K3 as per GOST 13846).

Operating temperature range:

  • from minus 60 to plus 100°C for K1 pipes;
  • from minus 46 to plus 100°C for K2 and K3 pipes;
  • from 0 to plus 650C for steam boilers, steam and gas turbines and other connections as per GOST 20700.

Overal dimensions and product weight are specified in the accompanying drawings.

Average service life, years – 10.

Operating medium characteristics, parameters and operating conditions shall be considered for material selection, i.e.:

  • design pressure
  • min ambient temperature
  • max operating medium temperature
  • chemical composition and properties of the working medium and environment (corrosive, explosive, erosive contaminants)

All bolting shall be made of materials as per GOST1759.0, GOST 20700, GOST 28919, API 6A ASTMA193/193M, ASTM A194/194M, ASTM A320/A320M, NACE MR 0175.

Required material properties

Standard materials σ0,2  ,
MPa  (psi)
σв   ,
MPa  (psi)
δ5  ,
%
ψ  ,
%
Hardness max
Chromium-molybdenum alloy steel Grade L7M as per ASTM A320/A320M 550 690 18 50 235 НВ or 99 НRВ
Corrosion-resistant nickel-chromium alloys 725 860 18 50 321 НВ or 35 НRС
Alloy steel Grade 2HM as per ASTM A194 / A194M 22 НRС
Chromium-molybdenum alloy steel Grade L7 as per ASTM A320/A320M 725 860 16 50 321 НВ or 35 НRС
Thermostable, heat-resistant alloy steel as per GOST 20700 Mechanical properties of longitudinal samples at normal (20C) temperature and hardness shall conform to Table 3 GOST 20700

Material selection based on bolting type and operating medium composition for flanges as well as on the operating temperature range shall conform to

Bolting type Standard materials
Studs for K1 flange connections Chromium-molybdenum alloy steel Grade L7 as per ASTM A320/A320M
Studs for K2/K3 flange connections Chromium-molybdenum alloy steel Grade L7M as per ASTM A320/A320M
Corrosion-resistant nickel-chromium alloys
Nuts for K1/K2/K3 flange connections Alloy steel Grade 2HM as per ASTM A194 / A194M
Studs and nuts for flange connections with a medium temperature from 0 C to + 650 C Thermostable, heat-resistant alloy steel as per GOST 20700

Marking on bolting ends shall contain:

  • manufacturer’s trademark
  • ASTM material grade
  • nominal thread size
  • full stud length

A batch tag shall contain the product drawing designation and the batch number.

Limited warranty period is 12 months, but not more than 18 months from the date of shipment from the manufacturer. During the warranty period, the manufacturer is responsible for the manufacturing quality and product functionality. During the warranty period, the manufacturer undertakes to eliminate detected faults at its own expense.

The warranty shall be void in case of:

  • damage caused by violation of conditions of transportation, storage or pipeline connection by the customer;
  • product use for purposes other than intended and parameters and media/environments not specified in the TU specification.