BS 6071:1981 pdf free download.Periodic inspection and maintenance of transportable gas containers for dissolved acetylene.
1 Scope
BS 6071 specifies requirements for the periodic inspection and maintenance of transportable dissolved-acetylene containers of both seamless and welded construction.
2 References
The titles of the publications referred to in this standard are listed on the inside back cover.
3 Definitions
For the purposes of BS 6071 the following definitions apply.
dissolved acetylene
acetylene that is dissolved under pressure in a solvent contained in a porous substance at ambient temperature and is released from the solvent without the application of heat
3.2
solvent-free acetylene
acetylene that is adsorbed on a porous substance at ambient temperature without the addition of solvent and is released from the porous substance without the application of heat
3.3
porous substance
a substance approved by the Health and Safety Executive that fills the container as completely as possible and has no deleterious action on the acetylene, the solvent or the container
3.4
corrosion
a chemical reaction on material that results in the removal of the surface of the material
NOTE Corrosion may take may forms, including:
a) chemical attack where the metal is dissolved by the reagents, such attack being general over the complete surface. localized (causing pitting), or a combination of the two; b) rusting caused by the combined action of moisture and air.
3.5
inspection
a complete visual examination by a competent
person
4 General requirements
4.1 All containers shall, before being charged with acetylene, be subjected to periodic inspection in accordance with this standard if they have not been previously inspected within the following intervals:
a) those containing high-porosity lime silica porous substance: after twelve months of issue into service and thereafter at intervals of five years;
10.3 Cavitation (non-monolithic porous substance). Cavitation shall be made good with the appropriate porous substance.
10.4 Compaction (non-monolithic porous substance). Any loss of compaction shall be made good with the appropriate porous substance.
10.5 Looseness (monolithic porous substance). The maximum allowable gap between the porous substance and the container wall shall be 0.5 % of the diameter or length of the container with an overall maximum of 3.2 mm. Any gap greater than this shall be cause for rejection.
10.6 Fire damage. Any sign of fire damage to the porous substance shall be cause for rejection.
11 Replacement of porous substance
Where the porous substance is to be replaced, the solvent and all traces of the original substance shall be removed and the inside of the container thoroughly cleaned. The internal surface of the container shall be examined in accordance with 7.2 as appropriate.
12 Inspection of container neck threads
12.1 General. The container neck threads shall be cleaned to remove particles of jointing or other foreign matter. They shall be inspected to ensure that they are of full form, clean and free from burrs and other imperfections.
12.2 Retapping of BS 341 taper threads. Where necessary, and where the design of the neck permits, taper threads may be retapped to ensure that there is the required number of effective threads in accordance with Table 3.
If the nominal size of the container neck thread has to be increased, this shall be done in accordance with Table 3; interpolated values are acceptable. If retapping has been undertaken, care shall be exercised to ensure that all swarf and foreign matter is removed.
13 Inspection and maintenance of valves
Each valve shall be inspected and maintained so that when it is reintroduced into service it will perform satisfactorily. In particular, all threads shall be checked to ensure that the thread diameters, form, length and taper are satisfactory.
If threads show signs of significant distortion, deformation or burring, these faults shall be rectified. Excessive thread damage or serious deformation of the valve body, handwheel, spindle or other component shall be cause for replacement.

Maintenance of the valve shall include general cleaning, together, where necessary, with replacement of worn or damaged components and packings. Where lubricants are used they shall be compatible with both the solvent and acetylene.
14 Replacement of neck filters
All filters and discs withdrawn from containers at each examination shall be replaced by new, using special tools as appropriate.
15 Revalving
Each container shall he revalved using a suitable jointing medium and the optimum torque necessary to ensure a gastight seal between the valve and container. The gas tightness of this connection and the valve assembly shall be checked by a leakage test.
Attention is drawn to Table 3 for the required minimum engagement of threads; there shall be an adequate stand-out in order that only fully formed threads are engaged.
A test date ring may be fitted over the valve stem prior to revalving.
16 Plugs
Where fitted, fusible or solid plugs or plugs fitted with a bursting disc shall be visually examined for damage or evidence of leakage. Any unsatisfactory plug shall be replaced following cleaning of the socket threads with the appropriate tap.
NOTE It is important that plugs arc not interfered with or further tightened.
17 Replenishment of solvent
Any deficiency of the solvent content of the container shall be made good before the container is passed for recharging. Care shall be taken to ensure that the correct solvent is used.
18 Cleaning and painting
Where necessary each container shall be carefully cleaned, marked and repainted maroon in accordance with BS 349.
19 Exemption label
When required to be fitted to the container, the exemption label shall be examined and cleaned so that the wording on it is legible. If the label is missing, damaged or illegible it shall be replaced and if loose it shall be securely fastened to the container.
22 Destruction of unserviceable containers
Containers that have been deemed unsuitable for further service shall, after the procedures specified in 5.1 and clause 8 have been followed, have the solvent and porous substance removed in a safe manner and shall be destroyed by the testing station, using one of the following methods.
a) The container shall be crushed by mechanical means.
b) An irregular hole shall be burned in the top dome of the container, equivalent in area to approximately 10 % of the area of the dome: or, in the case of thin-walled containers, the container shall be pierced in at least three places.
c) The container shall be destroyed by any alternative method approved by HM Inspector of Explosives.
Drilling a hole in a container shall not be considered as satisfying the requirements of this clause.