Petai

INTRODUCTION

The Standard Malaysian Name as well as the ASEAN Standard Name for the timber of Parkia spp.(Leguminosae). Vernacular names applied include kupang (Sabah), kerayong (Peninsular Malaysia) and petai (Peninsular Malaysia and Sarawak) with various epithets. Major species include P. timoriana, P. singularis and P. speciosa. The sapwood is white to yellow-brown and is extremely wide. The heartwood is seldom developed but if found is dark brown in colour.

Also known as Petai (Brunei); Ro yong (Cambodia); Olimbopo, Petai and Soga (Indonesia); and Sa To (Thailand).


DENSITY

The timber is soft to moderately hard and is light to moderately heavy with a density of 415-815 kg/m3 air dry. The timber is classified under Light Hardwood in Malaysia.


NATURAL DURABILITY

Durability tests of P. speciosa have been carried out at the Forest Research Institute Malaysia (FRIM). The results shows that the natural durability was 1 year and it is thus classified as non-durable. From the graveyard test of treated petai using creosote, it was found that the timber was still sound after 15 years (Tam, 1983).


PRESERVATIVE TREATMENT

The timber has been found to be extremely easy to treat.  


TEXTURE

Texture is rather coarse and uneven, with straight or shallowly interlocked grain.


STRENGTH PROPERTIES

The timber falls into Strength Group D (Burgess, 1958) or SG5 (MS 544:Part 2:2001).


Strength Properties of Petai (P. speciosa)

Test Condition

Modulus of Elasticity(MPa)

Modulus of Rupture(MPa)

Compression parallel to grain (MPa)

Compression perpendicular to grain (MPa)

Shear Strength (MPa) 

Green

9,600

49

24.3

-

8.3

Air dry

10,700

55

30.8

-

7.4


MACHINING PROPERTIES

It is easy to saw and work and produces a smooth planed surface.  


Machining Properties of Petai (P. speciosa) 

Test condition

Sawing

Planing

Boring

Turning

Re-sawing

Cross cutting

Ease of planing

Quality of finish

Ease of boring

Quality of finish

Ease of turning

Quality of finish

Green

easy

easy

easy

smooth

easy

rough

-

-

Air dry

easy

easy

easy

smooth

easy

rough

easy

rough


NAILING PROPERTY

The nailing property is rated as excellent.


AIR DRYING

The timber seasons fairly slowly with moderate amount of end-checking, insect and fungal attacks, slight amount of cupping, bowing, twisting and splitting. 13 mm thick boards take approximately 3.5 months to air dry, while 38 mm thick boards take 5 months.


SHRINKAGE

Shrinkage is rather low with radial shrinkage averaging 1.1% and tangential shrinkage averaging 1.9%.


DEFECTS

The logs of petai are free from the more usual defects, like 'spongy heart' and borer damage, but are very knotty near the pith. Desch (1941) stated that all samples in the Kepong wood collection were infected by blue-stain fungi and some had been attacked by powder-post beetles. Schneider as quoted by Desch (1941) added that the timber of P. javanica is rarely attacked by borers.

   
USES

The genus is more famous for its edible fruits rather than its timber, which has been successfully used in the manufacture of plywood as well as packing boxes and crates. The timber is also suitable for some interior works, like partitioning, stair railings and skirtings as well as furniture, joinery, cabinet making, disposable chopsticks and other temporary light constructional works.


REFERENCES

  1. Ahmad Shakri Mat Seman. 1984. Malaysian Timbers - Petai. Malaysian Forest Service Trade Leaflet No. 85. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 7 pp.
  2. Burgess, H. J. 1958. Strength Grouping of Malaysian Timbers. Malayan Forest Service Trade Leaflet No.25. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 15 pp.
  3. Desch, H. E. 1941. Manual of Malayan Timbers. Malay. For. Rec. No.15.
  4. Menon, P. K. B. 1986. Uses of Some Malaysian Timbers. Revised by Lim, S. C. Timber Trade Leaflet No. 31. The Malaysian Timber Industry Board and Forest Research Insitute Malaysia, Kuala Lumpur. 48 pp.
  5. MS 544: Part 2: 2001: Code Of Practice For Structural Use Of Timber. Permissible Stress Design of Solid Timber
  6. Tam, M. K. 1983. Unpublished report.
  7. Wong, T. M. 1982. A Dictionary of Malaysian Timbers. Revised by Lim, S. C. & Chung, R. C. K. Malayan Forest Record No. 30. Forest Research Institute Malaysia Kuala Lumpur. 201 pp.