GOST 3916.1 - 96

I N T E R G O V E R N M E N T A L S T A N D A R D

TECHNICAL REQUIREMENTS

Official Edition

• CLASSIFICATION AND DIMENSIONS
• TECHNICAL REQUIREMENTS
• ACCEPTANCE REGULATIONS
• DESIGNATION OF GRADES FOR FACE LAYERS OF PLYWOOD UNDER BY PRESENT STANDARD, GOST 10.55-71 END GOST 3916.1-89

1. 1. Plywood is subdivided into different grades in accordance with the surface external appearance; it is subdivided into different sorts in accordance with the glued junction water resistivity, and it is subdivided into polished and non-polished veneer according to the outer surface processing degree.

1. 1. 1. In accordance with the external layers appearance, plywood is subdivided into five grades: “E” (Elite), I, II, III, IV. The designations used for identification of the external layers grades are given in Appendix “A”.

1. 1. 2. In accordance with the glued junction water resistivity, plywood is subdivided into sorts:

- FSF (Exterior) - Plywood with enhanced water resistivity;

- FK (Interior) - Water - resistant plywood.

1. 1. 3. According to the degree of mechanical processing of the outer surface, plywood is subdivided into:

• non-sended plywood - NS;
• single sided sended plywood - 1S;
• double sided sended plywood - 2S.

* For example if you see in our database the field "Mark IBB2S", it is following: I - Interior glue; BB - birch/birch; 2S - double sided sended.

1. 2. D i m e n s i o n s.

1. 2. 1. Dimensions and number of plywood sheet layers should correspond to those indicated in Tables 1 and 2.

Table 1.

All dimensions in millimetres.

Table 2.

All dimensions in millimetres.

1. 2. 2. Sheets of plywood must be cut at right angle. The slant value should not exceed 2 mm per 1 m of length of a sheet edge.

1. 2. 3. Deviation from rectilinearity for the edges should not exceed 2 mm per 1 m of length of a sheet.

1. 3. Conventional designation for plywood should contain:

- product denomination;

- kinds of wood used for internal and external layers;

- sort of plywood ;

- combination of grades of sheets of wood used for external layers;

- emission class;

- kind of surface finish;

- dimensions;

- designation of the present Standard.

Example of conventional designation for a birch plywood with internal layers made of birch sheets of wood, having a Interior - sort, with an external layers sheets of wood combination of I / III, class of emission of E1, double - sided sended veneer, having the length of 2440 mm, width of 1525 mm, and thickness of 9 mm:

2. 1. C h a r a c t e r i s t i c s.

2. 1. 1. Deciduous kinds of wood are used in sheets for external layers in plywood production:

birch, alder, maple, elm, beech, aspen, poplar, and linden. In addition to the aforementioned, the following kinds of softwood are used in the form of sheets for internal layers: pine, spruce, abies, larch, and cedar.

The kind of wood used for veneer external layers is considered to be the material of the plywood .

Plywood made of one kind of wood, and veneer made of different kinds of wood are subdivided respectively into homogeneous and combined plywood .

With an even number of veneer sheet layers, two central layers should have the grain in parallel direction. The veneer sheet layers located symmetrically through the plywood thickness, should be made of wood of the same kind and thickness.

Thickness of veneer sheets used for external layers of plywood should not exceed 3.5 mm, and thickness of sheets used for internal layers should not exceed 4 mm.

2. 1. 2. Defects of timber and processing defects are not allowable in external layers of plywood , if said defects exceed the limits specified in Table 3.

2. 1. 3. Defects of timber and processing defects are allowable in internal layers of plywood , if said defects have no influence upon quality and dimensions of plywood , the requirements to the quality and dimensions specified in the present Standard.

2. 1. 4. Maximum quantities of different kinds of allowable blemishes and processing defects on the surface of plywood with external layers made of veneer sheets of the specified grades are indicated in Table 4.

Table 3. - Norms of limitation of timber blemishes and defects of processing.

Table 4.

Units: EACH.

2. 1. 5. Combinations of grades of external layers of veneer are specified in GOST 30427.

2. 1. 6. In plywood of up to 1525 mm wide, an E - grade external layer can be made of two stripes of veneer sheets of wood with junction in the centre of a sheet of veneer. In plywood having a width of 1525 mm, an E - grade external layer can be made of three stripes of veneer sheets of wood of equal width. External layers of grades I and II are allowed to be made of unlimited quantities of stripes of veneer sheets.

For the grades E, I, II junctions of veneer sheets should be directed parallel to the edges, and the stripes should be selected to have similar coloration.

2. 1. 7. Insertions made of veneer sheets should fit the surface, have good adhesion and provide concordance of their coloration and grain direction with that of the external layer plywood . For grades E and I, II the insertions colour should correspond to the coloration of the timber.

Putty should be selected to the coloration of timber of the particular grade, and should provide gluing of decoration materials; they should not crumble out under mechanical processing and bending of plywood , neither should they crack all over.

2. 2. Physical and mechanical parameters of plywood are indicated in Table 5.

Table 5.

2. 3. Content of formaldehyde in plywood should correspond to the data given in Table 6, depending on the class of emission.

Table 6.

2. 4. Account of plywood is made in square metres and / or in cubic metres. The volume of a sheet of plywood is determined with the accuracy of 0.00001 m³, the volume of a lot of plywood is determined with the accuracy of 0.01 m³. Area of a sheet of plywood is accounted with the accuracy of 0.01 m², total sheets area in a lot is accounted with the accuracy of 0,5 m².

2. 5. Marking is made with an indelible paint on the back side of each sheet of plywood with the indication of sort, grade of plywood , and the sorter number.

Marking is made on a pack of plywood , to include:

- name of country - manufacturer;

- name of manufacturing company and / or its trade mark;

- conventional designation of plywood ;

- number of sheets per pack;

- national seal of the certificate of compliance for the certified products.

Transportation marking is made in accordance with GOST 14192.

2. 6. Packing and wrapping.

2. 6. 1. Plywood should be packed in packages to have a weight not exceeding 1500 kg, separately, due to the kind of wood, sort, grade, class of emission, type of surface processing, and dimensions.

Where agreed, plywood can be packed in packages of different weight in accordance with the conditions of an agreement (contract).

2. 6. 2. Packing and wrapping of plywood to be supplied to the extreme Northern districts, and hardly accessible districts, is made in accordance with the Item 4. 6. 1, and GOST 15846.

3. 1. Plywood is accepted in lots.

A lot should contain plywood made of the same kind of wood, having the same sort, grade, class of emission, type of surface processing and dimensions of sheets.

A lot should be provided with one document to specify its quality, which document should include the following:

- name of country - manufacturer;

- name and / or the trade mark of manufacturing company and its legal address;

- conventional designation of plywood ;

- the volume or total sheets area in the lot;

- stamp of technical control;

- national seal of the certificate of compliance for the certified products.

3. 2. The quality and dimensions of sheets of plywood is verified by means spot check. Verification in the form of entire control is allowable in accordance with the conditions of an agreement (contract).

When performing spot check, the sheets of plywood are selected at random, according to GOST 18321, in quantity specified in Table 7.

Table 7.

Units: sheets of veneer.

3.3. Breaking points under folding, stretching, and static bending are checked for each sort of plywood , each thickness and layers number, with a frequency of not less than once per month. Verification is allowed to be performed for each lot, in accordance with the conditions of an agreement (contract), for which verification 0.1% of total sheets number, but no less than one sheet, should be selected from the lot.

3. 4. Formaldehyde content parameter is checked for Exterior - sort of plywood once in 30 days, and for Interior - sort of veneer once in 15 days.

Checking once in 7 days is allowed in accordance with the conditions of an agreement (contract).

5. 5. A lot is considered to meet the requirements of the present Standard and is accepted in case where in the samples from the lot:

- number of sheets of plywood not meeting the requirements of the Standard on dimensions, slant, rectilinearity, timber blemishes, and defects of processing, is less,

or equal to the acceptance number specified in Table 7;

- all plywood sheets are free from bubbles, exfoliation and bark;

- content of formaldehyde corresponds to the norms specified in Table 6.

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