Plywood Standard GBT 9846-2015

- May 09, 2019-

Plywood Standard GBT 9846-2015


This standard specifies the definition, category, requirements,testing manners,rules of inspection, marks, package, transportation and storage of plywood for general use.

 

 Size and Deviation

 Range of nominal thickness(t)

Unsanded board

Sanded board(surface)


Common difference of inner thickness

Difference of nominal thickness

Common difference of inner thickness

Difference of nominal thickness


t≤3

0.5

+0.4

-0.2

0.3

±0.2


3<t≤7

0.7

+0.5

-0.3

0.5

±0.3


7<t≤12

1.0

+(0.8+0.03t)

-(0.4+0.03t)

0.6

+(0.2+0.03t)

-(0,4+0.03t)


12<t≤25

1.5

0.6

+(0.2+0.03t)

-(0.3+0.03t)


t>25

0.8


 

The Appearance & Quality Requirements

 

Allowed Defects for Different Classes of Hardwood Plywood Appearance

Defects type

Item

Surface

Back face






Superior

First-class

Qualified








Pin holes

Allowed





Intergrown knot

Maximum single diameter/mm

10

20

Unlimited





Partiqlly intergrown knot, dead knot, bark pocket

Total number on 1m2's surface

Not allowed

4

6

Unlimited




Partiqlly intergrown knot

Maximum single diameter/mm

Not allowed

15(if the number ≤5, it shall be ignored)

Unlimited





Dead knot

Maximum single diameter/mm

Not allowed

4   (if the number ≤2, it shall be ignored)

15

Unlimited




Bark pocket

Single maximum length/mm

Not allowed

20(if the number ≤5, it shall be ignored)

Unlimited





Abnormal structure of wood

Allowed





 Cracks

Single maximum width/mm

Not allowed

1.5

for linden 0.5

3,

for linden1.5,

for wood from south China 4

6






Single maximum length/mm

200

wood from South China 250

400

for wood from south China 450

800

for wood from south China 1000






 Worm holes、dog holes, holes

Maximum single diameter/mm

Not allowed

4

8

15






Total number on 1m2's surface

4

Sieve pores are not allowed





 Discoloration

Shall not exceed % the area of board

Not allowed

30

Unlimited





Note 1:Streaks with light color shall be seen as color variation.

Note 2: For class 1 products, the width of streaks with deep color shall not exceed 2mm, and the length shall not exceed 20mm.

Note 3:For birch products,except for superior products, false heartwood is allowed, but the gloss of first-class products shall be harmonious.

Note 4: For first class birch products, dense brown or black pith flecks are not allowed.

Note 5: Sapwood and heartwood with different colors shall be seen as a case of color variation.





Decay

Not allowed

Initial decay is allowed if the strength is not influenced, but the area shall not

 exceed 1% of the board area.

Initial decay is allowed







Gum duct

Single maximum length/mm

Not allowed

150

Unlimited








Single maximum width/mm

10








Total number on 1m2's surface

4








Assembled gap on the surface

Single maximum width/mm

Not allowed

0.5

1

2









The single maximum length is % the length of board

10

30

50









Total number within a width of 1m

1

2

Unlimited









 Folded layers

Single maximum width/mm

Not allowed

8

10







The single maximum width is % the width of board

20

Unlimited







 Core gaps and overlaps

Core gaps and overlaps stick closely to the surface board

Single maximum width/mm

Not allowed

 

2

6

8




Total number within a width of 1m

2

Unlimited






Maximum gap width in other layers

8










gaps and overlaps of cross-band veneer

 

Single maximum width/mm

Not allowed

8







 Blistering、layering

Not allowed






 Dents,press marks,blisering

maximum area/mm2

Not allowed

50

400

Unlimited









Total number on 1m2's surface

1

4









 Burrs

shall not exceed % the the area of board

Not allowed

1

2

Unlimited









the depth shall not exceed/mm

0.2

Penetration is not allowed

 








The surface is sanded through

Total number on 1m2's surface

Not allowed

400

Unlimited





Glue penetration and other man-made contamination

Shall not exceed % the area of board

Not allowed

0.5

30

Unlimited





Repair patch, repair strip

Allowable number for well-made, firmly repaired ones

Not allowed

3

Unlimited

Unlimited





The cumulative area shall not exceed % the area of board

0.5

3





The crack shall not be longer than/mm

0.5

1

2





Include aluminum-made staple

  Not allowed






Deformity on the edge

within nominal size, shall not exceed /mm

 Not allowed

10



Other defects

Not allowed

Count them as their most similar defect types



 

Allowed Defects for Different Classes of Coniferous Tree Plywood Appearance

Defects type

Item

Surface

Back face



Superior

First-class

Qualified



Pin holes

Allowed



Intergrown knots,partially intergrown knot, dead knot, bark pocket

Total number on 1m2's surface

5

8

10

Unlimited



Intergrown knot

Maximum single diameter/mm

20

30,(if the number ≤10, it shall be ignored)

 

Unlimited



Partially intergrown knot,dead knot

Maximum single diameter/mm


5(if the number ≤2, it shall be ignored)

30(if the number ≤10, it shall be ignored)

Unlimited



Abnormal structure of wood

Allowed



Bark pocket、resin pocket

Total number on 1m2's surface

3

4

(if the number ≤10,

it shall be ignored)

10

(if the number ≤15, 

it shall be ignored)

Unlimited



Single maximum length/mm

15

30

Unlimited



Cracks

Maximum single width/mm

Not allowed

1

2

6



Single maximum length/mm

200

400

1000



Wormholes, dogholes

Maximum single diameter/mm

Not allowed

2

10

15



Total number on 1m2's surface

4

10( if the number ≤3, it shall be ignored)

Sieve pores are not allowed



Color variation

shall not exceed % the the area of board

Not allowed

Light color 10

Not allowed



Decay

Not allowed

1%, Initial decay is allowed if the strength 

is not influenced, but the area shall not 

exceed 1% of the board area.

Initial decay is allowed



Resinous wood(resinous streak)

Single maximum length/mm

Not allowed

150

Unlimited



Maximum single width/mm

10



Total number on 1m2's surface

4



Assembled gap on the surface

Single maximum width/mm

Not allowed

0.5

1

2



The single maximum length is % the length of board

10

30

50



Total number within a width of 1m

 

1

2

Unlimited



Folded layers

Single maximum width/mm

Not allowed

2

10



 The single maximum width is % the width of board

20

Unlimited



Core gaps and overlaps

Core gaps and overlaps stick closely to the surface board

Single maximum width/mm

Not allowed

2

4

8



Total number within a width of 1m

2

Unlimited



Maximum gap width in other layers

8



Gaps and overlaps of cross-band veneer

Single maximum width/mm

Not allowed

8



Blistering、layering

Not allowed



Dents,press marks,blisering

Single maximum area/mm2

Not allowed

50

400

Unlimited



Total number on 1m2's surface

2

6



Burrs

shall not exceed % the the area of board

Not allowed

5

20

 Unlimited



the depth shall not exceed/mm

0.5

Penetration is not allowed

 



The surface is sanded through

Total number on 1m2's surface

Not allowed

400

Unlimited



 

Glue penetration and other man-made contamination

 

 

Shall not exceed % the area of board

Not allowed

1

Unlimited



Repair patch, repair strip

Allowable number for well-made, firmly repaired ones

 Not allowed

6

 

Unlimited



The cumulative area shall not exceed % the area of board

1

5

Unlimited



The crack shall not be longer than/mm

0.5

1

2



Include aluminum-made staple

Not allowed



Deformity on the edge

within nominal size, shall not exceed /mm

 Not allowed

10



Other defects

Not allowed

Count them as their most similar defect types



 

Allowed Defects for Different Classes of Tropical Hardwood Plywood Appearance

Defects type

Item

Surface

Back face


Superior

First-class

Qualified


Pin holes

Allowed


Intergrown knot

Maximum single diameter/mm

10

20

Unlimited


Partially intergrown knot, dead knot, bark pocket

 

Total number on 1m2's surface

Not allowed

3

5

Unlimited


Partially intergrown knot

Maximum single diameter/mm

10,if the number ≤5, it shall be ignored)

 

Unlimited


Dead knot

Maximum single diameter/mm

4(if the number ≤2, it shall be ignored)

15

Unlimited


Abnormal structure of wood

Allowed


Cracks

Single maximum width/mm

Not allowed

1.2

2

6


Single maximum length/mm

250

350

800


Bark pocket

Total number on 1m2's surface

Not allowed

2

4

Unlimited


Single maximum length/mm

10(if the number ≤5, it shall be ignored)

Unlimited


Worm problems

Worm holes

Total number on 1m2's surface

Not allowed

8(if  ≤1.5mm, it shall be ignored)

8

15


Single maximum diameter/mm

2

 Sieve pores are not allowed


Worm ducts

Total number on 1m2's surface

Not allowed

2


Single maximum length/mm

10


Dog holes, holes

Single maximum diameter/mm

Not allowed

2

8

15


Total number on 1m2's surface

1

Unlimited


Discoloration

Shall not exceed % the area of board

Not allowed

5

Unlimited


Decay

Not allowed

1%

Initial decay is allowed if the strength is not influenced, but the area shall not exceed 1% of the board area.

Initial decay is allowed


Gum duct

Single maximum length/mm

Not allowed

150

Unlimited


Single maximum width/mm

10


Total number on 1m2's surface

4


Assembled gap on the surface

Single maximum width/mm

Not allowed

1

2


The single maximum length is % the length of board

30

50


Total number within a width of 1m

 

2

Unlimited


Folded layers

Single maximum width/mm

Not allowed

2

10


 The single maximum width is % the width of board

20

Unlimited


Core gaps and overlaps

Core gaps and overlaps stick closely to the surface board

Single maximum width/mm

Not allowed

2

4

8


Total number within a width of 1m

 

2

Unlimited


Maximum gap width in other layers

Not allowed

8


Gaps and overlaps of cross-band veneer

Single maximum width/mm

Not allowed

8


Blistering、layering

Not allowed


Dents, indentations, drums

Total number on 1m2's surface

Not allowed

1

4

Unlimited


Burrs

shall not exceed % the the area of board

Not allowed

1

25

Unlimited


Maximum depth

0.4

Penetration is not allowed


The surface is sanded through

Total number on 1m2's surface

 Not allowed

400

Unlimited


Glue penetration and other man-made contamination

Shall not exceed % the area of board

Not allowed

0.5

30

Unlimited


Repair patch, repair strip

Allowable number for well-made, firmly repaired ones

Not allowed

3

Unlimited

Unlimited


The cumulative area shall not exceed % the area of board

0.5

3


The crack shall not be longer than/mm

0.5

1

2


Include aluminum-made staple

 Not allowed


Deformity on the edge

within nominal size, shall not exceed /mm

 Not allowed

10


(24)Other defects

Not allowed

Count them as their most similar defect types


  

Moisture Content

Wood variety of plywood

Category


I、II Category

III Category


Hardwoods(include tropical hardwoods

5~14

5~16


Coniferous wood


Category I: The ones which can past boiling test and can be used in outdoor environment.


Category II:The ones which can past 63℃±3℃ hot water dipping test, can be made into wet conditions as moisture-resistant plywood.


Category III:The ones which can past 20℃±3℃ cold water dipping test, can be made into dry conditions as moisture-prone plywood.


  

Requirements for binding strength

Tree variety/Wood name/Name of foreign commercial goods

Category


I,II category

III category


Basswood, cypress, sample, paulownia wood, rubber wood, meranti, Okoume, white wutong, Anisoptera spp, Calophyllum inophyllum, eucalyptus wood

≥0.70

≥0.70


Northeast China ash, lotus wood, sweetgum, maple wood, elm, Chinese oak, apitong, cloning, kapur

≥0.80


Birch

≥1.00


Pinus massoniana, yunnan pine pine, larch, spruce, monterey pine

≥0.80


 

MOR and MOE Requirements

Item

t/mm


7≤t≤9

9<t≤12

12<t≤15

15<t≤21

t>21


MOR(modulus of rupture)

parallel to the grain

32.0

28.0

24.0

22.0

24.0


across the grain

12.0

16.0

20.0

20.0

18.0


MOE(modulus of elasticity)

parallel to the grain

5500

5000

5000

5000

5500


across the grain

2000

2500

3500

4000

3500


 

 

MARKS、PACKAGE、TRANSPORTATION AND STORAGE

 

Package 

The products shall be packed properly based on categories and specifications.Each package shall bear product name, wood variety of width of surface and cross-band veneer, grade, factory name, brand, size, quantity, product standard code and inspection labels with formaldehyde release limit marks.

 

Transportation and Storage

Products shall be kept safe from dampness, rain, exposure to strong sunlight and distortions during transportation or storage period.